The Professor reached the clay-pit, and searched the undulating surface of the heath for some sign of the remains of Dr. Morlandson’s laboratory. For some moments he failed to find it, and then, at last, he made out the jagged tooth of a broken wall thrust upwards from behind a clump of gorse bushes. This, no doubt, must be his goal. There was no path leading to it from the track, but the Professor, using his stick to feel the way, stepped out boldly across the heather, which yielded like a cushion to his footsteps. The distance from the track to the ruin must have been six or seven hundred yards. It took the Professor some little time to cover it, since he was obliged to make several detours in order to avoid clumps of gorse. But he reached it at last, and stood on the edge of what had once been a clearing, surveying the scene that lay before him. The cottage itself had completely vanished. All that remained of it was a mound thickly overgrown with weeds and coarse grass, from which protruded here and there fragments of charred beams and rafters. The encroaching heath had hidden any signs of any garden there might once have been, and it was impossible for the Professor to form any idea of what the place had looked like while it was still standing. But the laboratory, having been built of concrete, had defied the utter obliteration to which the rest of the premises had succumbed. Its broken walls, rough and jagged, stood up in a gaunt rectangle, roofless, their foundations hidden deep in the all-effacing vegetation, but still marking without fear of error the site upon which the building had stood. The Professor pushed through the weeds and undergrowth until he reached the gap in the wall where the door had been. The door was still there, rusty and twisted, lying almost hidden at the base of the wall, where it had been thrown by Dr. Morlandson’s would-be rescuers. It was a plain sheet of iron, fitted with hinges and a lock. The Professor glanced at it, then passed through the door-way into the space enclosed between the walls. Something, perhaps a grass-snake, rustled among the grasses as he entered. The laboratory had been a fairly spacious room, about thirty feet by fifteen. Of its interior fittings nothing whatever remained. As the Professor advanced into the interior of the space his boots struck metal at every other step. He stooped and probed with his stick, and brought to light a twisted and shapeless tangle of iron, which might once have been the frame of a skylight. He examined it for a moment, and then cast it aside, with a nod of comprehension. The walls themselves still showed upon their interior surface the signs of having been subjected to an enormous heat. He poked about inside the laboratory for a short while longer, then came out and sat down upon the mound which had once been a cottage.