“It would appear so.”
“At least we may accept it as a working hypothesis. We will suppose, then, that something was burned in each case which produced an atmosphere causing strange toxic effects. Very good. In the first instance—that of the Tregennis family—this substance was placed in the fire. Now the window was shut, but the fire would naturally carry fumes to some extent up the chimney. Hence one would expect the effects of the poison to be less than in the second case, where there was less escape for the vapour. The result seems to indicate that it was so, since in the first case only the woman, who had presumably the more sensitive organism, was killed, the others exhibiting that temporary or permanent lunacy which is evidently the first effect of the drug. In the second case the result was complete. The facts, therefore, seem to bear out the theory of a poison which worked by combustion.
“With this train of reasoning in my head I naturally looked about in Mortimer Tregennis’s room to find some remains of this substance. The obvious place to look was the talc shelf or smoke-guard of the lamp. There, sure enough, I perceived a number of flaky ashes, and round the edges a fringe of brownish powder, which had not yet been consumed. Half of this I took, as you saw, and I placed it in an envelope.”
“Why half, Holmes?”
“It is not for me, my dear Watson, to stand in the way of the official police force. I leave them all the evidence which I found. The poison still remained upon the talc had they the wit to find it. Now, Watson, we will light our lamp; we will, however, take the precaution to open our window to avoid the premature decease of two deserving members of society, and you will seat yourself near that open window in an armchair unless, like a sensible man, you determine to have nothing to do with the affair. Oh, you will see it out, will you? I thought I knew my Watson. This chair I will place opposite yours, so that we may be the same distance from the poison and face to face. The door we will leave ajar. Each is now in a position to watch the other and to bring the experiment to an end should the symptoms seem alarming. Is that all clear? Well, then, I take our powder—or what remains of it—from the envelope, and I lay it above the burning lamp. So! Now, Watson, let us sit down and await developments.”
They were not long in coming. I had hardly settled in my chair before I was conscious of a thick, musky odour, subtle and nauseous. At the very first whiff of it my brain and my imagination were beyond all control. A thick, black cloud swirled before my eyes, and my mind told me that in this cloud, unseen as yet, but about to spring out upon my appalled senses, lurked all that was vaguely horrible, all that was monstrous and inconceivably wicked in the universe. Vague shapes swirled and swam amid the dark cloud-bank, each a menace and a warning of something coming, the advent of some unspeakable dweller upon the threshold, whose very shadow would blast my soul. A freezing horror took possession of me. I felt that my hair was rising, that my eyes were protruding, that my mouth was opened, and my tongue like leather. The turmoil within my brain was such that something must surely snap. I tried to scream and was vaguely aware of some hoarse croak which was my own voice, but distant and detached from myself. At the same moment, in some effort of escape, I broke through that cloud of despair and had a glimpse of Holmes’s face, white, rigid, and drawn with horror—the very look which I had seen upon the features of the dead. It was that vision which gave me an instant of sanity and of strength. I dashed from my chair, threw my arms round Holmes, and together we lurched through the door, and an instant afterwards had thrown ourselves down upon the grass plot and were lying side by side, conscious only of the glorious sunshine which was bursting its way through the hellish cloud of terror which had girt us in. Slowly it rose from our souls like the mists from a landscape until peace and reason had returned, and we were sitting upon the grass, wiping our clammy foreheads, and looking with apprehension at each other to mark the last traces of that terrific experience which we had undergone.
“Upon my word, Watson!” said Holmes at last with an unsteady voice, “I owe you both my thanks and an apology. It was an unjustifiable experiment even for one’s self, and doubly so for a friend. I am really very sorry.”
“You know,” I answered with some emotion, for I have never seen so much of Holmes’s heart before, “that it is my greatest joy and privilege to help you.”
He relapsed at once into the half-humorous, half-cynical vein which was his habitual attitude to those about him. “It would be superfluous to drive us mad, my dear Watson,” said he. “A candid observer would certainly declare that we were so already before we embarked upon so wild an experiment. I confess that I never imagined that the effect could be so sudden and so severe.” He dashed into the cottage, and, reappearing with the burning lamp held at full arm’s length, he threw it among a bank of brambles. “We must give the room a little time to clear. I take it, Watson, that you have no longer a shadow of a doubt as to how these tragedies were produced?”
“None whatever.”
“But the cause remains as obscure as before. Come into the arbour here and let us discuss
