“A good start, Tom Swift,” complimented Mr. Parker.  “Is it always as easy as this?”

“Starting always is,” was the answer, “though, as the Irishman said, coming down isn’t sometimes quite so comfortable.”

“Bless my gizzard!  That’s so,” cried the eccentric Mr. Damon.  “Can we vol-plane to earth in the Red Cloud, Tom?”

“Yes, but not as easily as in the Butterfly.  However I hope we will not have to.  Now, Mr. Damon, if you will just take charge of the steering apparatus for a minute, I want to go aft.”

“What for?”

“I wish to see if everything is all right.  I can’t imagine why Eradicate was making those queer motions.”

Mr. Damon, who knew how to operate the Red Cloud, was soon guiding her on the course, while Tom made his way to the rear compartments, through the motor room, where the stores of supplies and food were kept.  He made a careful examination, looking from an after window, and even going out on a small, open platform, but could discover nothing wrong.

“I guess Rad was just capering about without any special object,” mused Tom, but it was not long after this that they learned to their dismay, that the colored man had had a method in his madness.

On his way back through the motor room Tom looked to the machinery, and adjusted some of the auxiliary oil feeders.  The various pieces of apparatus were working well, though the engine had not yet been speeded up to its limit.  Tom wanted it to “warm-up” first.

“Everything all right?” asked Mr. Damon, as Tom rejoined them in the pilot house, which was just forward of the living room in the main cabin.

“Yes, I can’t imagine what made Rad act that way.  But I’ll set the automatic steering gear now, Mr. Damon, and then you will be relieved.”

Mr. Jenks was gazing off toward the west—­to where he hoped to discover the secret of Phantom Mountain.

“How do you like it?” asked Tom.

“It’s great,” replied the diamond man.  “I’ve never been in an airship before, and it’s different than what I expected; but it’s great!  It’s the only craft that will serve our purpose among the towering mountain peaks, where the diamond makers are hidden.  I hope we can find them.”

In a little while the Red Cloud was skimming along at faster speed, guided by the automatic rudders, so that no one was needed in the pilot house, since there was no danger of collisions.  Airships are not quite numerous enough for that, yet, though they may soon become so.

Tom and the others devoted several hours to arranging their staterooms and bunks, and getting their clothing stowed away, and when this was done Mr. Parker and Mr. Jenks sat gazing off into space.

“It’s hard to realize that we are really in an airship,” observed the diamond man.  “At first I thought I would be frightened, but I’m not a bit.  It doesn’t seem as if anything could happen.”