Porter, the housekeeper, told us that she herself fainted upon entering the room and had afterwards opened the window. In the second case⁠—that of Mortimer Tregennis himself⁠—you cannot have forgotten the horrible stuffiness of the room when we arrived, though the servant had thrown open the window. That servant, I found upon inquiry, was so ill that she had gone to her bed. You will admit, Watson, that these facts are very suggestive. In each case there is evidence of a poisonous atmosphere. In each case, also, there is combustion going on in the room⁠—in the one case a fire, in the other a lamp. The fire was needed, but the lamp was lit⁠—as a comparison of the oil consumed will show⁠—long after it was broad daylight. Why? Surely because there is some connection between three things⁠—the burning, the stuffy atmosphere, and, finally, the madness or death of those unfortunate people. That is clear, is it not?”

“It would appear so.”