chamber twice as large as actuality; why this illusion should be necessary or even desirable was utterly beyond Thvall's comprehension. Reflecting surfaces in utter dissociation with any recognizable form of apparatus whatsoever were a complete enigma to him.
THE floor of this chamber was littered with no less than twenty skeletons. Some were still partly clothed in garments of vegetable, mineral and animal fiber; some wore loose-fitting circlets of metallic alloys around their tinier appendages; many of the circlets held geometrically carved bits of crystallized carbon in claw-like sockets. Lifting and examining a small, glass-dialed mechanism which lay beside one of the skeletons, Thvall discovered that it was operated by an internal spring which had, however, lost its tension; he rewound the spring by turning a ratcheted pin provided for the purpose, and discovered that the mechanism produced a regular pulsation, while three small indicators beneath a transparent portion of the mechanism's shell revolved at proportionate though greatly dissimilar velocities. Correctly assuming that the mechanism was a device for measuring the passage of time, Thvall replaced the watch beside the skeleton of its owner and glided toward the deeper recesses of the chamber.
Here he discovered a number of doors arranged in an orderly row, and, investigating one which was not fully closed and which slid open easily, he found that it opened upon a chimney-like well. Within the well were a number of taut steel cables, which supported a square metal cage at a level slightly beneath the door. Thvall had opened the cage, Thvall saw at once, was designed to be raised and lowered from level to level of the building. Far above, a tiny pinpoint of brilliant light told Thvall that the well extended to the top of the building; he instantly determined to ascend the shaft and view the city from that vantage-point. He squirmed up the elevator shaft like a gargantuan knot of writhing serpents, and, reaching the elevator motors, squeezed upward past them and into a small, many-windowed chamber. Here an iron door provided egress to the roof of the building. Thvall opened the door and squirmed through.
On the roof of the building, in the clean, sharp sunlight, Thvall put down his instruments and weapons and sedately capered. This world was so fair, so bountiful—and, as yet, so undeveloped! There was no doubt now that its ruling race were exceedingly primitive, but they possessed intelligence of a sort, too; if they proved peaceable and friendly Thvall's people could teach them so much—so much!—in return for a bit of the planet's desert land and a single lake of water. Probably the first boon Thvall's kind would confer upon this world's people would be conquest of the plague which had slain this city's inhabitants. Yes, that would certainly be done first. . . .
The roof on which Thvall stood was flat, and surrounded by a low parapet. It was encumbered by only two objects, the small structure which housed the elevator motors and a huge torpedo-shaped, steel cylinder which lay near a corner of the parapet. Some of the parapet bricks were broken, and there was a long, dull scar on the roof. Obviously the cylinder had been dropped from a low altitude, had struck the parapet a glancing blow, and had then slithered across the roof.
What was the thing, and why had it been dropped on this roof?
