I knew, though, that Triton was of the same approximate size as Earth's own moon, and revolved around the great planet at the same approximate distance as Earth's own moon, roughly a quarter of a million miles. As we had noted from our space-flier in flashing out toward Neptune, its moon was now behind the great planet, that is on the other side of it from the sun, but due to the sharp inclination of the plane of Triton's orbit around Neptune, it was so much higher than its great planet in space as to make it possible to see the single moon, even from Neptune's sunward side. And now as our eleven cylinders shot toward it, it was spreading out across the black vault of the heavens before and above us, until at last we were within a few thousand miles of it and the speed of the cylinder was perceptibly decreasing beneath the controls of the three at the central standard. Smoothly the cylinder, and the ten behind it, slowed, until they were racing forward at a comparatively low velocity. Triton's dull-gleaming sphere filled the heavens before us. Behind and a little below the great green disk of Neptune, belted with the vast cloud-masses of its immense atmosphere, loomed almost as great as ever to our eyes. And far beyond it there burned the sun's bright little disk, just above the huge sphere of Neptune, and visible to us through the thinner vapors of Neptune's uppermost atmosphere. We turned back toward the nearer world of Triton. As the cylinders rushed on toward it, all the suspense of expectation and mystery that had been ours since our first arrival at the strange dead world of Neptune gripped us now with renewed power. And as Marlin and I stared ahead we were aware that the cylinders were dropping, swinging about our pivoted seats and dropping toward the surface of Triton that seemed now to gleam beneath us. Toward it we smoothly shot, and as Marlin and I gazed intently down we saw that there were below none of the great cloud-masses that wreathed the surface of mighty Neptune. Instead was only a smooth and strangely gleaming surface that we could but vaguely glimpse, and the sight of which made my heart pound in sudden anticipation. Could the thing be--could it be that here upon Triton as upon Neptune----? But my wondering speculations were cut abruptly short by reality as we shot lower toward the surface of Triton, as that surface came clearly at last to the eyes of Marlin and myself, bringing involuntary exclamations of amazement from us. For that surface was metal! Triton was shielded on all sides by a giant metal roof similar to that which enclosed great Neptune itself! * * * * *