Abruptly Sam stepped out beside me. There was almost a grin on his lean, tanned face, and he looked somehow very confident and resourceful. I felt a great wave of faith in him and in the wonderful machine beneath our feet, rocking silently in the strange, smooth sea. Impulsively I reached out my hand to him, and he took it with a smile. "I know how you feel, Mel. But we're still kicking!" "But the ocean?" I asked again. "What could hold it up?" "I've been doing some pretty stiff thinking along that line. I have a theory that might help you, even if I have missed the point. You know we came through the red gas that makes the curious sky we see. The gas was just below the water. It's evidently radioactive, or it wouldn't be luminous. Its emanations might change the gravity of the water above!" "Negative gravity or levitation?" "Something of the kind. You know that science has held for a long time that there is no reason, _per se_, to doubt the existence of substances that would repel instead of attracting one another. In fact, the mutual repulsion of the like poles of a magnet is, in a way, an illustration of that very thing. Even assuming the existence of substances of negative gravity, they would not be found on the surface of the earth, for they would escape into space as fast as liberated. The phlogiston of the old alchemists, by the way, was supposed to be such a substance. "But suppose the gravity of the water is negatived by the gas. Water, you know, has the property of becoming radioactive after it has been exposed to radium emanations, and it is logical enough for it to assume the qualities of the gas. The water next to the gas may support that above." "But it looks as if the gas would bubble out, like air under water," I said. "That was the principal objection to the theory. But we know from our pressure readings that the water is not resting heavily on the gas. If it is supported by the negative gravity of its lower stratum, the equilibrium is very delicate, but it would be naturally maintained. "Suppose the roof of water is lifted. The gas and atmosphere below, being given more room, would expand. Consequently the gas would be brought less intimately into contact with the water, the negativing effect would be reduced, and the balance would be restored. Conversely, a sinking would compress the gas, increase its effect, and bring back the balance. Even if the water sank in one place and was lifted in another, the difference in the density of the gas at various altitudes would maintain the equilibrium." "Yes. Yes, I believe I see. A thousand thanks! It makes me feel a lot better to see how it could be," I said, admiring the wonderful readiness with which he had formulated his theory. "But can you say how the gas came to be here, and how there happens to be breathable air beneath it?"