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