A moment we stared toward each other, and then I had snapped open one of the switches before me, turning the ray-direction dial, sending down slantwise toward the metal surface a force-ray, instead of the vertical ray that had upheld our flier. The pressure of this slanting ray at once sent our ball-like space-flier moving forward across Neptune's surface, across the smooth vast dark metal plain whose presence was so astounding to us. I glanced at the outside-temperature dial as we shot forward, saw that the atmosphere through which we moved though dense was cold indeed, hardly above zero in temperature. Then with Marlin and Whitely and Randall I turned my attention to the smooth great metal surface over which we were driving. On and on we shot, though, without finding any slightest change or opening or structure in that unending dark metal surface, that swept away in its vast, bare curve to the horizons, which were very far from us, so great was the radius of curvature of Neptune's mighty sphere. But after tense moments of this fruitless watch from our racing flier, Whitely uttered a low exclamation and pointed ahead, toward a round lighter circle in the dark metal plain far to the left, a circular opening in the giant metal shield! None other of us spoke as we gazed toward that opening, but at once I had sent the space-flier rushing toward it. As we raced nearer to it we saw that that opening's circle was a full five hundred feet in diameter, and that we could see down through it a great, bright-lit space beneath! Tensely we watched, until in another moment I had sent the space-flier directly above the great opening, so that it hovered motionless above the circular opening's center. And as it hung there we four, forgetful for the moment of all else, were gazing down through the space-flier's window through that opening, down into the great more brightly-lit space that we could see beneath, beneath the huge metal shield that covered all this world!