"But I have already been to the level above," I said, "and I have seen many of the wonders of Fal Sivas's inventions."

She gave little cry of alarm, then. "Oh, Vandor, you are lost!" she cried. "Now you will never leave this terrible place."

"On the contrary, I shall leave it tonight, Zanda," I told her. "Fal Sivas has agreed that I should do so."

She shook her head. "I cannot understand it," she said, "and I shall not believe it until after you have gone."

Toward evening Fal Sivas sent for me. He said that he wanted to talk to me about some further changes in the gearing of the motor, and so I did not get out that night, and the next day he had me in the shops directing the mechanics who were working on the new gears, and again he made it impossible for me to leave the premises.

In one way or another, he prevented it night after night; and though he didn't actually refuse permission, I began to feel that I was, indeed, a prisoner.

However, I was much interested in the work in the shops and did not mind much whether I went out or not.

Ever since I had seen Fal Sivas's wonder-craft and had listened to his explanation of the marvellous mechanical brain that controlled it, it had been constantly in my thoughts. I saw in it all the possibilities of power for good or evil that Fal Sivas had visualized, and I was intrigued by the thought of what the man who controlled it could accomplish.

If that man had the welfare of humanity at heart, his invention might prove a priceless boon to Barsoom; but I feared that Fal Sivas was too selfish and too mad for power to use his invention solely for the public good.

Such meditation naturally led me to wonder if another than Fal Sivas could control the brain. The speculation intrigued me, and I determined to ascertain at the first opportunity if the insensate thing would respond to my will.

That afternoon Fal Sivas was in his laboratory, and I was working in the shops with the poor manacled artisans. The great ship lay in the adjoining room. Now, I thought, presented as good a time as any to make my experiment.

The creatures in the room with me were all slaves. Furthermore, they hated Fal Sivas; so it made no difference to them what I did.

I had been kind to them and had even encouraged them to hope, though they could not believe that there was any hope. They had seen too many of their number die in their chains to permit them to entertain a thought of escape. They were apathetic in all matters, and I doubt that any of them noticed when I left the shop and entered the hangar where the ship rested upon its scaffolding.

Closing the door behind me, I approached the nose of the craft and focused my thoughts upon the brain within. I imparted to it the will to rise from its scaffolding as I had seen Fal Sivas cause it to do and then to settle down again in its place. I thought that if I could cause it to do that, I could cause it to do anything that Fal Sivas could.

I am not easily excited; but I must confess that my every nerve was tense as I watched that great thing above me, wondering if it would respond to those invisible thought-waves that I was projecting into it.

Concentrating thus upon this one thing naturally curtailed the other activities of my mind, but even so I had visions of what I might accomplish if my experiment proved successful.

I presume that I had been there but a moment, yet it seemed a long while; and then slowly the great craft rose as though lifted by an invisible hand. It hovered for a moment ten feet above its scaffolding, and then it settled down to rest again.

As it did so, I heard a noise behind me; and, turning quickly, I saw Fal Sivas standing in the doorway of the shop.

CHAPTER VII. THE FACE IN THE DOORWAY

Nonchalance is a corollary of poise. I was thankful at that moment that the poise gene of some ancient forebear had been preserved in my line and handed down to me. Whether or not Fal Sivas had entered the room before the ship came to rest again upon its scaffolding, I did not know. If not, he had only missed the sight by a matter of a split second. My best momentary defense was to act on the assumption that he had not seen, and this I determined to do.

Standing there in the doorway, the old inventor was eyeing me sternly. "What are you doing in here?" he demanded.

"The invention fascinates me; it intrigues my imagination," I replied. "I stepped in from the shop to have another look at it. You had not told me that I should not do so."

He knitted his brows in thought. "Perhaps, I didn't," he said at last; "but I tell you now. No one is supposed to enter this room, unless by my express command."

"I will bear that in mind," I said.

"It will be well for you if you do, Vandor."

I walked then toward the door where he stood, with the intention of returning to the shop; but Fal Sivas barred my way.

"Wait a moment," he said, "perhaps you have been wondering if the brain would respond to your thought-impulses."

"Frankly, I have," I replied.

I wondered how much he knew, how much he had seen. Perhaps he was playing with me, secure in his own knowledge; or perhaps he was merely suspicious and was seeking confirmation of his suspicion. However that might be, I was determined not to be trapped out of my assumption that he had not seen and did not know.

"You were not, by any chance, attempting to see if it would respond?" he asked.

"Who, other than a stupid dolt, once having seen this invention, would not naturally harbor such a thought?" I asked.

"Quite right, quite right," he admitted; "it would only be natural, but did you succeed?" The pupils of his eyes contracted; his lids narrowed to two ominous slits. He seemed to be trying to bore into my soul; and, unquestionably, he was attempting to read my mind; but that, I knew, he could not accomplish.

I waved my hand in the direction of the ship. "Has it moved?" I asked with a laugh.

I thought that I saw just a faint hint of relief in his expression, and I felt sure then that he had not seen.

"It would be interesting, however, to know whether the mind of another than myself could control the mechanism," he said. "Suppose you try it."

"It would be a most interesting experiment. I should be glad to do so. What shall I try to have it do?"

"It will have to be an original idea of your own," he told me; "for if it is my idea, and I impart it to you, we cannot be definitely sure whether the impulse that actuates it originated in your brain or mine."

"Is there no danger that I might unintentionally harm it?" I asked.

"I think not," he replied. "It is probably difficult for you to realize that that ship sees and reasons. Of course, its vision and its mental functioning are purely mechanical but none the less accurate. In fact, I should rather say, because of that, more accurate. You might attempt to win the ship to leave the room. It cannot do so because the great doors through which it will eventually pass out of this building are closed and locked. It might approach the wall of the building, but the eyes would see that it could not pass through without damage; or, rather, the eyes would see the obstacle, transmit the impression to the brain, and the brain would reason to a logical conclusion. It would, therefore, stop the ship or, more likely, cause it to turn the nose about so that the eyes could seek a safe avenue of exit. But let us see what you can do."

I had no intention of letting Fal Sivas know that I could operate his invention, if he did not already know it; and so I tried to keep my thoughts as far from it as possible. I recalled football games that I had seen, a five-ring circus, and the Congress of Beauties on the Midway of the 1893 Chicago World's Fair. In fact, I tried to think of anything under the sun rather than Fal Sivas and his mechanical brain.