"And now," he said, "I will tell you what I know. I found the secret of the door mechanism even as you did, Dr. Goodwin. But by carelessness, my condensers were broken. I was forced to wait while I sent for others--and the waiting might be for months. I took certain precautions, and on the first night of this full moon I hid myself within the vault of Chau-ta-leur." An involuntary thrill of admiration for the man went through me at the manifest heroism of this leap in the dark. I could see it reflected in Larry's face. "I hid in the vault," continued Marakinoff, "and I saw that which comes from here come out. I waited--long hours. At last, when the moon was low, it returned--ecstatically--with a man, a native, in embrace enfolded. It passed through the door, and soon then the moon became low and the door closed. "The next night more confidence was mine, yes. And after that which comes had gone, I looked through its open door. I said, 'It will not return for three hours. While it is away, why shall I not into its home go through the door it has left open?' So I went--even to here. I looked at the pillars of light and I tested the liquid of the Pool on which they fell. That liquid, Dr. Goodwin, is not water, and it is not any fluid known on earth." He handed me a small vial, its neck held in a long thong. "Take this," he said, "and see." Wonderingly, I took the bottle; dipped it down into the Pool. The liquid was extraordinarily light; seemed, in fact, to give the vial buoyancy. I held it to the light. It was striated, streaked, as though little living, pulsing veins ran through it. And its blueness, even in the vial, held an intensity of luminousness. "Radioactive," said Marakinoff. "Some liquid that is intensely radioactive; but what it is I know not at all. Upon the living skin it acts like radium raised to the nth power and with an element most mysterious added. The solution with which I treated him," he pointed to Huldricksson, "I had prepared before I came here, from certain information I had. It is largely salts of radium and its base is Loeb's formula for the neutralization of radium and X-ray burns. Taking this man at once, before the degeneration had become really active, I could negative it. But after two hours I could have done nothing." He paused a moment. "Next I studied the nature of these luminous walls. I concluded that whoever had made them, knew the secret of the Almighty's manufacture of light from the ether itself! Colossal! Da! But the substance of these blocks confines an atomic--how would you say--atomic manipulation, a conscious arrangement of electrons, light-emitting and perhaps indefinitely so. These blocks are lamps in which oil and wick are electrons drawing light waves from ether itself! A Prometheus, indeed, this discoverer! I looked at my watch and that little guardian warned me that it was time to go. I went. That which comes forth returned--this time empty-handed.