The Red Cloud was fitted up to accommodate about ten persons, though it was seldom that this number was carried.  Two persons could successfully operate the machinery.  There were sleeping berths, and in the main cabin a sitting-room, a dining-room, and a kitchen.  There was also the motor compartment, and a steering tower, from which the engines could be controlled.

It was in this craft that the seekers after the diamond makers proposed undertaking the trip.  Mr. Damon came on from his home in Waterfield about two days before the date set to leave, and Mr. Jenks, had, three days before this, taken up his abode at the Swift home.  Mr. Parker, as has been stated, was already there, and he had put in his time making a number of scientific observations, though he had made no more predictions.

Nothing more had been seen of the mysterious man who had warned Tom, and the young inventor and Mr. Jenks began to hope that they had thrown their enemies off the track.

“Though I don’t imagine they’ll give up altogether,” said Mr. Jenks.  “They’re too desperate for that.  We’ll have trouble with them yet.”

“Well, it can’t be helped,” decided Tom.  “We’ll try and be ready for it, when it comes,” and then, dismissing the matter from his mind, he busied himself about the airship.

The food and supplies had all been put aboard, and they expected to start the next morning.  In order to make sure that any stones which they might succeed in getting from the diamond makers were real gems, a set of testing apparatus was taken along.  Mr. Parker had had some experience in this line, and, in spite of the fact that he might make direful predictions, Tom was rather glad, after all, that the scientist was going to accompany them.

“But what is worrying me,” said Mr. Damon, “is what we are going to do after we get to Phantom Mountain.  What are your plans, Mr. Jenks?  Will you go in, and demand your share of the diamond-making business?”

“I have a right to it, as I invested a large sum in it, and I am entitled to more than a half-share.  But, of course, I can’t say what I’ll do until I get there.  We may have to act very secretly.”

“I’m inclined to think we will,” said Tom.  “My plan would be to gain access to the cave, if possible, and watch them at work.  We might be able to discover the secret of making diamonds, and, after all, that’s what you want, isn’t it, Mr. Jenks?”

“Yes, I paid my money for the secret, and I ought to have it.  If I can get it quietly, so much the better.  If not, I’ll fight for my rights!” and he looked very determined.

“Bless my powder horn!” cried Mr. Damon.  “That’s the way to talk!  And so we’re to go cruising about in the air, looking for a mountain shaped like a man’s head.”

“That’s it,” a greed Mr. Jenks, “and when we find it we will be near Phantom Mountain, and the diamond makers.”

The final details were completed that night.  The last of the supplies had been put aboard, the larder was well stocked, the diamond testing apparatus was stored safely away, and all that remained was for the adventurers to board the Red Cloud in the morning, and soar away.