He called to me once more, and I noticed an odd repression in his voice. “Assure yourself, and me, of the safety of the jar. Nothing else. If by chance you notice aught beyond, keep the knowledge of it locked in your breast--never mention it or refer to it in any way.” Full of dull foreboding of some dread discovery, I left him and went slowly down the stairs. I paused outside the ominous door, with a thought that a little whisper of laughter had reached my ears from its inner side. Then, muttering abuse on myself, for my cowardice, I pushed resolutely at the cumbrous oak and swung it open. A cold, vault-like breath of air sighed out on me, and the marrow in my bones was conscious of a little chill and shiver. But I strode across the floor without further hesitation and fetched from my pocket the iron key. The hole it fitted into was near the edge of the great box that inclosed the wheel. Standing there in close proximity to the latter, I was struck by the subdued character of the flapping and washing sounds within. Heard at a distance, they seemed to shake the whole building with their muffled thunder. Here no formidable uproar greeted me; and so it was, I conclude, from the concentration of noise monopolizing my every sense. I put in the key, swung open the door--and there before me was a section of a huge disk going round overwhelmingly, and all splashed and dripping as it revolved, with great jets of weedy-smelling water. I say “disk,” for the arms to this side had been boarded in, that none, I supposed, might gather hint of what lay beyond. The eyes into which the shaft ends of the wheel fitted were sunk in the floor level, flush with the lintel of the cupboard door that lay furthest from the window; so that only the left upper quarter of the slowly spinning monster was visible to me. It turned in an oblong pit, it seemed, wooden in its upper part, but going down into a narrow gully of brick, at the bottom of which the race boomed and roared with a black sound of fury. If the hollow thunder of the unseen torrent had been dismal to hear, the sight of it boiling down there in its restricted channel was awful indeed. From the forward tunnel through which it escaped into the tail bay, a thin streak of light tinged the plunging foam of it with green phosphorescence and made manifest the terror of its depths. For all my dread of the place, a strange curiosity had begun to usurp in me the first instincts of repulsion. Though I had been in the room some minutes, no malignant influence had crept over me as yet, and a hope entered me that by thus forcing myself to outface the fear I had perhaps triumphed over its fateful fascination. Leaving the door of the cupboard open, I hurried from the room, and so to the rear of the building and the platform outside, where the heads of the sluices were that regulated the water flow. Here, removing the pin, I dropped the race hatch and so cut off the stream from the wheel.