In the center of the pit was a titanic, shining green cylinder, perhaps a hundred feet in diameter and five hundred in length. A river of gleaming silver fluid ran from an opening in the rock, through a great open aqueduct, and poured into the cylinder in the middle of the upperside. At each end of the colossal cylinder rose a metal tower. At the top of each tower was a fifty-foot globe of blue crystal, slowly turning. Between and above the spheres arched a high-flung span of white fire--a great pulsing sheet of milky opalescent light--that roared and crackled like a powerful electric discharge, and lit the chasm with an unearthly radiance. Toward the farther side of the floor was a second enormous machine, apparently unconnected with the first, resembling a vast telescope. The white metal tube was a full two hundred feet in length, mounted on massive metal supports. It did not seem to be in action. The barrel of it was pointing at the sky, like a telescope, or a cannon. Then I saw a row of openings low down in the side of the vast green cylinder, with shafts of bright green light pouring from them. And I saw tiny human figures working feverishly about them. They had escaped my observation at first, so far away was the floor of the pit. Now I saw that they were taking great blocks of a luminous green substance from the doors in the cylinder and carrying them to the tube that was pointing at the sky. I saw now that the bodies of the toilers were purple. There was something in their motion that reminded me of ants. I was amazed at their strength and agility, at their ceaseless, machine-like activity. They never looked about, never paused, never rested. They were like machines, or animated corpses, driven to endless toil by some strange force. I remembered the time I had splashed the white fluid on my arm, turning it purple, and the strange excitement of my nerves. At once I linked up the raids on _Astran_, the bracelet that Naro had found on the dead purple beast, and what Austen had told me of superior beings who enslaved the purple things. I knew that I looked upon the captured men and women of _Astran_, simply _man-machines_ in this strange place! Perhaps they were already dead. Certainly they moved, not by their own volition, but by a stronger mechanical power. They must have been under the absolute hypnotic control of the higher intelligences, who treated their unfortunate captives, perhaps with the argent liquid, to convert them into unearthly machines, of super-human strength.