But Professor Roumann was not one to give up easily. He kept at his task, aided occasionally by Professor Henderson and by the boys whenever they could do anything.

Finally the German cried out:

"Ah, I have discovered the trouble. It is that scoundrel Axtell! See!"

And reaching into the interior of the machine he pulled out a small magnet. To it was attached a card, on which was written:

"I told you I would have my revenge!" It was signed with Axtell's name.

"This was the dastardly plot he evolved," said Professor Roumann. "He slipped this magnet into the equilibrium machine, knowing that in time it would cause a deflection of the delicate needles, and so shift the centre of gravity. He must have done this as a last resort, and to provide for his revenge in case we discovered him on board after we started. It was a cruel revenge, for had I not discovered it we would soon all be killed."

"Is the machine all right now?" asked Jack.

"It will be in a few minutes. Here, take this magnet and put it as far away from the engine room as possible."

It was the work of but a few minutes, now that the disturbing element was removed, to readjust the gravity machine, and Mr. Roumann called:

"Look out, now, everybody! We're going to turn right side up again!"

As he spoke he turned a small valve wheel. There was a clanging of heavy ballast weights, which slid down their rods to the proper places.

Then, like some great fish turning over in the water, the _Annihilator_ turned over in the ether, and was once more on her proper keel, if such a shaped craft can be said to have a keel.

Of course, the occupants of the s.p.a.ce ship went slipping and sliding back, even as they had fallen ceilingward before, but they were prepared for it, and no one was hurt. From the galley came a chorus of cries, as pots and pans once more scattered about Washington, but there was no more soup to spill.

As soon as the _Annihilator_ was righted, the Cardite motor began to work automatically, and once more the projectile, with the seekers of the moon, was shooting through s.p.a.ce at their former speed. They had lost considerable distance, but it was easy to make it up.

"Well, that _was_ an experience," remarked Jack, as he and his chum began picking up the tools and other objects that were scattered all about by the change in equilibrium.

"I should say yes," agreed Mark. "I'm glad it didn't happen at dinner time. That fellow Axtell is a fiend to think of such a thing."

"Indeed, he is! But we're all right now, though it did feel funny to be turned upside down."

An inspection of the projectile was made, but they could discover no particular damage done. She seemed to be moving along the same as before, and, except for the upsetting of things in the store-room, it would hardly have been known, an hour later, that a dreadful accident was narrowly averted.

Washington made more soup, and soon had a fine meal ready, over which the travellers discussed their recent experience.

"And when do you think we will arrive?" asked Jack of Mr. Henderson.

"We ought to be at the moon inside of two days now. We have not made quite the speed we calculated on, but that does not matter. I think we will go even more slowly on the remainder of the trip, as I wish to take some scientific observations."

"Yes, and so do I," added Mr. Roumann. "I think if we make fifteen miles a second from now on we will be moving fast enough."

Accordingly the Cardite motor was slowed down, and the projectile shot through s.p.a.ce at slightly reduced speed, while the two scientists made several observations, and did some intricate calculating about ether pressure, the distance of heavenly bodies and other matters of interest only to themselves.

It was on the afternoon of the third day following the turning turtle of the _Annihilator_ that Mark, who was looking through a telescope in the pilot-house, called out: "I say, Jack, look here!"

"What's the matter?" asked his chum.

"Why, we're rushing right at the moon! I can see the mountains and craters on it as plain as though we were but five miles away!"

"Then we must be nearly there," observed Jack. "Let's tell the others, Mark."

They hurried to inform the two professors, who at once left their tables of figures and entered the steering chamber. Then, after gazing through the gla.s.s, Mr. Henderson announced: "Friends, we will land on the moon in half an hour. Get ready."

"Are we really going to be walking around the moon inside of thirty minutes?" asked Mark.

"I don't know about walking around on it," answered the German. "We first have to see if there is an atmosphere there for us to breathe, and whether the temperature is such as we can stand. But the Annihilator will soon be there."

The speed of the Cardite motor was increased, and so rapidly did the projectile approach Luna that gla.s.ses were no longer needed to distinguish the surface of the moon.

There she floated in s.p.a.ce, a great, silent ball, but not like the earth, pleasantly green, with lakes and rivers scattered about in verdant forests. No, for the moon presented a desolate surface to the gaze of the travellers. Great, rugged mountain peaks arose all about immense caverns that seemed hundreds of miles deep. The surface was cracked and seamed, as if by a moonquake. Silence and terrible loneliness seemed to confront them.

"Maybe it's better on some other part of the surface," said Jack, in a low voice.

"Perhaps," agreed Mark. "It's certainly not inviting there."

Nearer and nearer they came to the moon. It no longer looked like a great sphere, for they were so close that their vision could only take in part of the surface, and it began to flatten out, as the earth does to a balloonist.

And the nearer they came to it the more rugged, the more terrible, the more desolate did it appear. Would they be able to find a place to land, or would they go hurtling down into some awful crater, or be dashed upon the sharp peak of some mountain of the moon?

It was a momentous question, and anxious were the faces of the two professors.

"Mr. Henderson, if you will undertake to steer to some level place, I will take charge of the motor," suggested Mr. Roumann. "I will gradually reduce the speed, and get the repelling machine in readiness, so as to render our landing gentle."

"Very well," responded the aged scientist, as he grasped the steering wheel.

The progress of the _Annihilator_ was gradually checked. More and more slowly it approached the moon. The mountains seemed even higher now, and the craters deeper.

"What a terrible place," murmured Jack. "I shouldn't want to live there."

"Me either," said Mark.

"Can you see a place to land?" called Professor Roumann through the speaking-tube from the engine room to the steering tower.

"Yes, we seem to be approaching a fairly level plateau," was Mr.

Henderson's reply.

"Very well, then, I'll start the repelling machine."

The Cardite motor was stopped. The projectile was now being drawn toward the moon by the gravity force of the dead ball that once had been a world like ours. Slowly and more slowly moved the great projectile.

There was a moment of suspense. Mr. Henderson threw over the steering wheel. The _Annihilator_ moved more slowly. Then came a gentle shock.

The dishes in the galley rattled, and there was the clank of machinery.

The Shanghai rooster crowed.

"We're on the moon at last!" cried jack, peering from an observation window at the rugged surface outside.

"Yes; and now to see what it's like," added Mark. "We'll go outside, and----"