Fal Sivas seemed to have forgotten nothing, yet all his thought and care and efficiency would have gone for nothing had I not been able to seize the ship.

His own cowardice would have prevented him from using it; and of course he would not have permitted another to take it out, even had he believed that another brain than his could have operated it, which he had been confident was not possible.

My inspection of the ship completed, I went into the control room and looked out through one of the great eyes. The heavens were a black void shot with cold and glittering points of light. How different the stars looked when one had passed beyond the atmosphere of the planet.

I looked for Thuria. She was nowhere in sight. The discovery was a distinct shock. Had the mechanical brain failed us? While I was wasting my time inspecting the ship, was it bearing us off into some remote corner of space?

I am not inclined to lose my head and become hysterical when confronted by an emergency; nor, except when instant action is required, do I take snap judgment.

I am more inclined to think things out carefully, and so I sat down on a bench in the control room to work out my problem.

Just then Jat Or came in. "How long have I been sleeping?" he asked, "Not long," I replied; "you had better go back and get all the rest that you can."

"I am not sleepy," he said. "In fact it is rather difficult to contemplate sleep when one is in the midst of such a thrilling adventure. Think of it, my prince--"

"Vandor," I reminded him.

"Sometimes I forget," he said; "but, anyway, as I was saying, think of the possibilities; think of the tremendous possibilities of this adventure; think of our situation."

"I have been thinking of it," I replied a little gloomily.

"In a few hours we shall be where no other Barsoomian has ever been- upon Thuria."

"I am not so sure of that," I replied.

"What do you mean?" he asked.

"Take a look ahead," I told him. "Do you see anything of Thuria?"

He looked out of one of the round ports and then turned to the other. "I don't see Thuria," he said.

"Neither do I," I replied. "And do you realize what that suggests?"

He looked stunned for a moment. "You mean that we are not bound for Thuria-that the brain has erred?"

"I don't know," I replied.

"How far is it from Barsoom to Thuria?" he asked.

"A little over 15,700 haads," I replied. "I estimated that we should complete the trip in about five zodes."

Just then Thuria hurtled into view upon our right, and Jat Or voiced an exclamation of relief. "I have it," he exclaimed.

"What?" I asked.

"Your mechanical brain is functioning better than ours," he replied. "During the ten zodes of a Barsoomian day, Thuria revolves about our planet over three times; so while we were travelling to the path of her orbit she would encircle Barsoom one and a half times."

"And you think the mechanical brain has reasoned that out?"

"Unquestionably," he said; "and it will time our arrival to meet the satellite in its path."

I scratched my head. "This raises another question that I had not thought of before," I said.

"What is that?" asked Jat Or.

"The speed of our ship is approximately 3250 haads per zode, whereas Thuria is travelling at a rate of over 41,250 haads during the same period."

Jat Or whistled. "Over twelve and a half times our speed," he exclaimed. "How in the name of our first ancestor are we going to catch her?"

I made a gesture of resignation. "I imagine we shall have to leave that to the brain," I said.

"I hope it doesn't get us in the path of that hurtling mass of destruction," said Jat Or.

"Just how would you make a landing if you were operating the ship with your own brain?" I asked.

"We've got to take Thuria's force of gravity into consideration," he said.

"That is just it," I replied. "When we get into the sphere of her influence, we shall be pulled along at the same rate she is going; and then we can make a natural landing."

Jat Or was looking out at the great orb of Thuria on our right. "How perfectly tremendous she looks," he said.. "It doesn't seem possible that we have come close enough to make her took as large as that."

"You forget," I said, "that as we approached her, we commenced to grow smaller-to proportion ourselves to her size. When we reach her surface, if we ever do, she will seem as large to us as Barsoom does when we are on its surface."

"It all sounds like a mad dream to me," said Jat Or.

"I fully agree with you," I replied, "but you will have to admit that it is going to be a most interesting dream."

As we sped on through space, Thuria hurtled across our bow and eventually disappeared below the Eastern rim of the planet that lay now so far below us.

Doubtless, when she completed another revolution, we should be within the sphere of her influence. Then, and not until then, would we know the outcome of this phase of our adventure.

I insisted now that Jat Or return to the cabin and get a few hours' sleep, for none of us knew what lay in the future and to what extent our reserves of strength, both physical and mental, might be called upon.

Later on, I called Jat Or and lay down myself to rest. Through it all, Zanda slept peacefully; nor did she awaken until after I had had my sleep and returned to the control room.

Jat Or was sitting with his face glued to the starboard eye. He did not look back at me, but evidently he heard me enter the cabin.

"She is coming," he said in a tense whisper. "Issus! What a magnificent and inspiring sight!"

I went to the port and looked out over his shoulder. There before me was a great world, one crescent edge illuminated by the sun beyond it. Vaguely I thought that I saw the contour of mountains and valleys, lighter expanses that might have been sandy desert or dead sea bottom, and dark masses that could have been forests. A new world! A world that no earthman nor any Barsoomian had ever visited.

I could have been thrilled beyond the power of words to express at the thought of the adventure that lay before me had my mind not been so overcast by fear for the fate of my princess. Thoughts of her dominated all others, yet they did not crowd out entirely the sense of magnificent mystery that the sight of this new world aroused within me.

Zanda joined us now; and as she saw Thuria looming ahead, she voiced a little exclamation of thrilled excitement. "We are very close," she said.

I nodded. "It will not be long now before we know our fate," I said. "Are you afraid?"

"Not while you are with me," she answered simply.

Presently I realized that we had changed our course. Thuria seemed directly beneath us now instead of straight ahead. We were within the sphere of her influence, and were being dragged through space at her own tremendous velocity.

Now we were spiralling downward; the brain was functioning perfectly.

"I don't like the idea of landing on a strange world at night," said Jat Or.

"I am not so enthusiastic about it myself," I agreed. "I think we had better wait until morning."

I then directed the brain to drop to within about two hundred haads of the surface of the satellite and cruise slowly in the direction of the coming dawn.

"And now, suppose we eat while we are waiting for daylight," I suggested.

"Is there food on board, master?" inquired Zanda.

"Yes," I replied, "you will find it in the storeroom abaft the cabin."

"I will prepare it, master, and serve you in the cabin," she said.

As she left the control room, Jat Or's eyes followed her. "She does not seem like a slave," he said, "and yet she addresses you as though she were your slave."

"I have told her that she is not," I said, "but she insists upon maintaining that attitude. She was a prisoner in the house of Fal Sivas, and she was assigned to me there to be my slave. She really is the daughter of a lesser noble-a well-bred, intelligent, cultured girl."