This was to take from the cabinets in the cylinder's side a number of small metal objects that seemed to be disks of gray metal a few inches across with flexible metal straps attached to them. These the Neptunians attached to the bottom or ends of their round, short limbs, as though little round sandals of metal. Then at the order of their leader they took other disks and attached them to the feet of Marlin and myself, one to each foot, binding them to our soles by passing the flexible straps up around our ankles. The thing was as puzzling to Marlin as to myself, for the moment, nor could we understand its object until, a moment later, the Neptunians began to pass out of the cylinder to the paving of the compartment outside. For as they did so I had reached toward one of the unused disks to examine it and had uttered an exclamation to find that, though so small in size and thickness, it was of many pounds weight! Yet as Marlin and I, in answer to the leader's order and gesture, passed out of the cylinder to the landing-compartment's floor, we could not feel at all that weight of dozens of pounds which had been fastened to our feet! Abruptly, though, light came to my perplexed mind. "Triton!" I exclaimed. "It's of about the same size as Earth's moon and hasn't much more gravitational power. And these Neptunians, used to the far greater gravitational power of Neptune, have to use these weights to add to their weight here on Triton to make it possible for them to move as always!" Marlin's eyes widened, and then he nodded. "It must be so," he said. "I wondered when I saw them from above how these creatures of Neptune could move so freely on its smaller moon." It was, indeed, a simple, yet ingenious device which the Neptunians had adopted. Accustomed as they had been to the great gravitational power of Neptune, seventeen times that of Earth, their squat, strange bodies owing their form to that great gravitational power, their muscles would have sent them through the air of Triton in immense and uncontrollable leaps at each step, so much smaller was the moon-world's gravitational power. So they had devised these small disks which fitted to the end of their strange limbs, and which, though so small and thin, yet had great weight, no doubt because the atoms of their substance had been compressed closely together for the purpose. The Neptunians had used disks of some thickness for themselves, and had used thinner ones for Marlin and myself, their smaller weight just sufficing to counteract the difference in gravitational power between Earth and Triton. And now, as we stepped out into the landing-compartment with our guards, it seemed as though we were walking with lead-weighted shoes at the ocean's bottom.