It was obvious at a glance that the story of the fuller's-earth was the merest fabrication, for it would be absurd to suppose that so powerful an engine could be designed for so inadequate a purpose. The walls were of wood, but the floor consisted of a large iron trough, and when I came to examine it I could see a crust of metallic deposit all over it. I had stooped and was scraping at this to see exactly what it was when I heard a muttered exclamation in German and saw the cadaverous face of the colonel looking down at me.
"'What are you doing there?' he asked.
"I felt angry at having been tricked by so elaborate a story as that which he had told me. 'I was admiring your fuller's-earth,' said I; 'I think that I should be better able to advise you as to your machine if I knew what the exact purpose was for which it was used.' "The instant that I uttered the words I regretted the rashness of my speech. His face set hard, and a baleful light sprang up in his grey eyes.
"'Very well,' said he, 'you shall know all about the machine.' He took a step backward, slammed the little door, and turned the key in the lock. I rushed towards it and pulled at the handle, but it was quite secure, and did not give in the least to my kicks and shoves. 'Hullo!' I yelled. 'Hullo! Colonel! Let me out!' "And then suddenly in the silence I heard a sound which sent my heart into my mouth. It was the clank of the levers and the swish of the leaking cylinder. He had set the engine at work. The lamp still stood upon the floor where I had placed it when examining the trough. By its light I saw that the black ceiling was coming down upon me, slowly, jerkily, but, as none knew better than myself, with a force which must within a minute grind me to a shapeless pulp. I threw myself, screaming, against the door, and dragged with my nails at the lock. I implored the colonel to let me out, but the remorseless clanking of the levers drowned my cries. The ceiling was only a foot or two above my head, and with my hand upraised I could feel its hard, rough surface. Then it flashed through my mind that the pain of my death would depend very much upon the position in which I met it. If I lay on my face the weight would come upon my spine, and I shuddered to think of that dreadful snap. Easier the other way, perhaps; and yet, had I the nerve to lie and look up at that deadly black shadow wavering down upon me? Already I was unable to stand erect, when my eye caught something which brought a gush of hope back to my heart.