I do not know just what my auditors expected in the way of an explanation of the mystery when they followed me to the green room—possibly some well-constructed or finely drawn theory. When I pointed to the chandelier, they all looked a bit nonplused, and nobody said anything for several moments. Then McQuade remarked, in his quiet voice, with a shade of comprehension in his tone and expression: "How do you make that out, Sir?"

The chandelier to which I had pointed was an old-fashioned one, of the kind in general use in the early fifties. It was, I fancied, originally made for a room with a somewhat higher ceiling. The ceilings in the wings of The Oaks were unusually low, and the extreme lower end of the chandelier extended to a point not much over six feet from the floor. I judged this, because I am myself five feet eleven, and I could just pass beneath it without striking it. It hung in the center of the room, and about three feet from the side of the bed, which, on account of its great size, extended far out from the wall against which it was placed. The chandelier was of dark bronze or bronzed iron, and consisted of a heavy central stem, from the lower end of which extended four elaborately carved branches, supported by heavy and useless chains reaching to a large ball about midway up the stem. Below the point from which these four arms sprung was a sort of circular bronze shield, or target, and from the lower face of this, in the center, projected an octagonal ornamental spike, about two and a half inches long, terminating in a sharp point. The whole thing was ugly and heavy, and seemed in design more suitable to a hall or library than a bedroom. Almost directly beneath it, but somewhat nearer to the side of the bed, stood the low bench or stool, not over five inches high, the use of which I have already mentioned. I explained the tragedy to the detective and the others as I knew it must have happened.

"Last night," I said, "I was unable to open either the window in the south or that in the west wall, because of the driving rain. The same conditions, as you will remember, existed upon the fatal night which Mr. Ashton spent here. For some reason, which I hope to explain presently, we were both nearly suffocated while asleep, and rose suddenly in bed, with but one thought, one desire, to get a breath of fresh air. The window in the west wall, directly opposite the bed, attracted us. In Mr. Ashton's case, no doubt, the face of Li Min, peering in from without, increased his terror. Like myself, he sprang up and dashed toward the window, placing his right foot, as I did, upon the low stool beside the bed. His first dash forward and upward, to a standing position, like my own, brought his head, elevated by the height of the stool, in contact with the spike upon the lower end of the chandelier with great force. The spike entered his head, fracturing the skull. He was a taller and heavier man than myself, and the force of the contact as he sprang forward and upward must have been terrific. In my case, owing to my having jumped from the bed at a slightly different point, I struck the spike only a glancing blow, which was sufficient however to render me unconscious for several minutes. I fell to the floor, senseless, but in a short time I struggled to my knees and managed, by crawling painfully to the door, to escape from the room. The interval, from the time I first fell to the time I reached the hall and again became unconscious, must have been very short."

"Why?" asked McQuade, who, like the others, followed my every word with intense interest.

"Because, had the time been very long, I, like Mr. Ashton, should never have risen at all. You would have found me here this morning, as he was found."

"But why?" asked Major Temple.

For answer I took a box of wax tapers from my pocket and lighted one. "Have you ever heard of the Cave of Dogs, near Naples?" I inquired.

"Carbon dioxide," gasped the Major with a look of comprehension.

Sergeant McQuade looked blank, and I saw that to him neither my question nor the Major's answer had conveyed any definite meaning. "Look," I cried, as I held the match out before me, where it burned with a bright, clear flame.

McQuade's mystification increased. I think he wondered if I were trying to play some practical joke upon him. But, when I slowly lowered the taper until it reached a point a few inches above my knee, and its flame faded away and then suddenly went out, as though the match had been plunged into a basin of water, his expression slowly cleared, and he gave a significant grunt. "Carbonic-acid gas," he said. "I understand. But where does it come from?"