"With this beginning he worked on, with other sketches and diagrams, establishing a slender line of communication between us, while those of our party watched in fascinated horror. At the end of an hour or more of this the things left us, through the vestibule-chamber, leaving us all in a strange state of wonder and fear. There was but little conversation on the part of any of us, and though we examined our prison carefully there seemed no chance whatever for escape; so the hours that followed passed in a semi-lassitude and silence, broken only by a sketchy meal from our own stores, after which most of our party resigned themselves to sleep. The air, we noted, remained quite pure, and was apparently made artificially by these creatures in some way, and pumped to us from outside. "The next day passed in the same way, and the next, and the next, strange nightless and dawnless days, eternally lit by the perpetual white radiance, which followed one another like the time-periods of a dream. In those days, however, the creatures who were our captors persisted in endeavoring to establish communication with us, for their own purposes, and gradually Lewis and I attained to an exchange of ideas with them. Their purpose, we found, was to question us concerning the world above, particularly concerning our nations and cities and their relation to the sea. We did not understand the purpose of those questions, then, but bit by bit during that exchange of ideas we came to learn something of their own history and plans, and began at last to understand what terrible peril was hanging above our world. "These creatures, as we had guessed, were native to the sea as man is native to the land, developed from the lower forms of sea-creatures in the remote past just as man developed from the lower land ones. Life began in the sea, as you know, and these slug-beings had developed into intelligence and power while man was still a half-ape roaming the barren plains. They had built their great globe-cities at the sea's bottom, and for their greater convenience had lit them with the light-producing mechanisms on the globes, which set up a permanent excitation or vibration of the ether, of a frequency that formed perpetual light-vibrations. In their hidden depths they reigned, lords of the sea. "But their domains were steadily diminishing. You know that since the dawn of time earth's seas have dwindled steadily, following the laws of molecular motion, that slowly those seas have retreated and dwindled, as on every planet they do, as on Mars they did eons ago. And since the slug-people could live only in the terrific pressures of the great depths their own realms were swiftly shrinking. They must either form some plan to halt the dwindling of the seas, or face certain extinction.