Our stunned, astounded exclamation sounded together there as we gazed downward from our flier, whose drop I had instinctively halted. For it was metal indeed that lay beneath us, a gigantic surface of smooth dark metal or metallic substance that glinted dully in the pale light that fell on it, and that stretched away in all directions to the horizons, completely covering the giant planet Neptune as far as we could see! A metal-covered world! In amazement, in awe, we stared down upon it in that moment. For we had expected many things, many aspects which the surface of Neptune might have had, frozen ice-fields or flaming craters or even a liquid world, but never had we expected what we now saw beneath us. Never had we expected to find the huge planet thus sheathed in a dark metal covering that apparently extended over all its gigantic surface! And in all its vast smooth expanse, we saw, there was no higher structure of any sort, nothing but the level plain of smooth dark metal, sweeping far away to the flat horizons. "Neptune a metal-covered world! And I think I see why, now," said Marlin quickly as we gazed down. "I think that I can understand why the beings of Neptune have covered their world with this shield----" "But what lies beneath it?" Randall asked. "Do you mean that these beings of Neptune----" "I mean that beneath this great shield they have built must lie the real world of the beings of Neptune--must lie the source of the giant force-ray that they're stabbing toward the sun!" "But how to get down inside?" said Whitely. "There seems no opening in this gigantic metal shield----" "We must go on, then," Marlin told us. "Must go on until we find some way of getting beneath, since beneath that shield there lies our goal!"