instrument of retribution in this man's case, and you must take the utmost care of yourself until your mission is accomplished. He knows the value of your evidence better than you do, and it is still worth his while to get rid of you if he can. But you, I am sure, are at least as anxious as we are to see him hanged."
"I'd sooner twist his neck with my own hands," said I.
"I daresay you would," said Thorndyke, " and it is perfectly natural that you should. But it is not desirable. This is a case for a few fathoms of good, stout, hempen rope, and the common hangman. The private vengeance of a decent man would be an undeserved honour for a wretch like this. So you must stay here quietly for a few days more and give us a little help when we need it."
Thorndyke's decision was not altogether unwelcome. Shaken as I was by the shock of this horrible tragedy, I was in no state to return to the solitude of my lodgings. The quiet and tactful sympathy of my two friends—or I should rather say three, for Polton was as kind and gentle as a woman—was infinitely comforting and their sober cheerfulness and the interest of their talk prevented me from brooding morbidly over the catastrophe of which I had been the involuntary cause. And, dreadful as the associations of the place were, I could not but feel that those of my older resorts would be equally painful. For me, at present, the Heath would be haunted by the figure of poor Letitia, walking at my side, telling me her pitiful tale and so pathetically craving my sympathy and friendship. And the Highgate Road could not but wring my heart with the recollection of that evening when we had walked together up the narrow lane—all unconscious of a black-hearted murderer stealing after us and foiled only by that futile spy—when, as we said good-bye I had kissed her and she had run off blushing like a girl.
Moreover, if Thorndyke's chambers were fraught with terrible and gloomy associations, they were also pervaded by an atmosphere of resolute, relentless preparation which was itself a relief to me; for, as the first shock of horrified grief passed, it left me possessed by a fury of hatred for the murderer and consumed by an inextinguishable craving for vengeance. Nor by the time of suspense so long as we had anticipated, as the very next morning a letter arrived from the Home Office containing the necessary authority to make the proposed examination and informing Thorndyke that on the following day the police would take possession of the ashes, which would be delivered to him by an officer who would remain to witness the examination and to resume possession of the remains when it was concluded.
I saw very little more of Thorndyke that day, but gathered that he was busy making the final arrangements for the important work of the morrow and clearing off various tasks so as to leave himself in from engagements. Nor did I enjoy much of Jervis's society, for he, too, was anxious to have the day free for the "Crucial Experiment," which was—we hoped—to solve the mystery of Septimus Maddock's death and explain the villain Samway's strange vindictiveness towards me.
Left to myself, and by no means enamoured of my own society, I wandered up to the laboratory to see what Polton was doing and to distract my gloomy thoughts by a little gossip with him on the various technical processes of which he possessed so much curious information. I found him arrayed in a white apron, with his sleeves turned up, busily occupied with what I took to be a slab of dough, which he had spread on a pastry board and was levelling with a hard-wood rolling-pin. He greeted me, as I entered with his queer, crinkly smile, but made no remark; and I stood awhile in silence, watching him cut the paste in halves, sprinkle it with flour, fold it up and once more roll it out into a sheet with the wooden pin. "Is this going to be a meat pie, Polton?" I asked, at length.
His smile broadened at my question—for which I suspect he had been waiting. "I don't think you'd care much for the flavour of it, if it was, sir," he answered. "But it does look like dough, doesn't it. It's moulding-wax; a special formula of the Doctor's own."
"I thought that white powder was flour."
"So it is, sir; the best wheaten flour. It's lighter than a mineral powder and more tenacious. You have to use some powder to reduce the stickiness of the wax, especially in a soft paste like this, which has a lot of lard in it."
"What are you going to use it for?" I asked.
"Ah!" exclaimed Polton, pausing to give the paste a vicious whack with the rolling-pin, "there you are, sir. That's just what I've been asking myself all the time I've been roiling it out. The Doctor, sir—God bless him—is the most exasperating gentleman in the world. He fairly drives me mad with curiosity, at times. He will give me a piece of work to do—something to make, perhaps—with full particulars—all the facts, you understand, perfectly clear and exact, with working drawings if necessary. But he never says what the thing is for. So I make a hypothesis for myself—whole bundles of hypotheses, I make. And they always turn out wrong. I assure you, sir," he concluded with solemn emphasis, "that I spend the best part of my life asking myself conundrums and giving myself the wrong answers."
"I should have thought," said I, "that you would have got used to his ways by now."
"You can't get used to him," rejoined Polton. "It's impossible. He doesn't think like any other man. Ordinary men's brains are turned out pretty much alike from a single mould, like a batch of pottery. But the Doctor's brain was a special order. If there was any mould at all, that mould was broken up when the job was finished."
"What you mean is," said I, "that he has a great deal more intelligence than is given to the rank and file of humanity."
"No, I don't," retorted Polton. "It isn't a question of quantity at all. It's a different kind of intelligence. Ordinary men have to reason from visible facts. He doesn't. He reasons from facts which his imagination tells him exists, but which nobody else can see. He's like a portrait painter who can do you a likeness of your face by looking at the back of your head. I suppose it's what he calls constructive imagination, such as Darwin and Harvey and Pasteur and other great discoverers had, which enabled them to see beyond the facts that were known to the common herd of humanity."
I was somewhat doubtful as to the soundness of Polton's views on the transcendental intellect, though respectfully admiring of the thoughtfulness of this curious little handicraftsman; accordingly I returned to the more concrete subject of wax. "Haven't you any idea what this stuff is going to be used for?"
"Not the slightest," he replied. "The Doctor's instructions were to make six pounds of it, to make it soft enough to take a squeeze of a stiff feather if warmed gently, and firm enough to keep its shape in a half-inch layer with a plaster backing, and to be sure to have it ready by to-morrow morning. That's all. I know there's an important analysis on to-morrow and I suppose this wax has got something to do with it. But, as to what moulding wax can have to do with a chemical analysis, that's a question that I can't make head or tail of."
Neither could I, though I had more data than Polton appeared to possess. Nor could Jervis, to whom I propounded the riddle when he came in to tea. We went up to the laboratory together and inspected, not only the wax, but the exterior of three large parcels addressed to Professor Woodfield, care of Dr. Thorndyke, and bearing the labels of a firm of wholesale chemists. But neither of us could suggest any solution of the mystery; and the only result of our visit to the laboratory was that Polton was somewhat scandalized by the conduct of his junior employer, who consoled himself for his failure by executing with the wax, a life-sized and highly grotesque portrait of Father Humperdinck.
XXI. The Final Problem
At exactly half-past eleven in the following forenoon, Professor Woodfield arrived, bearing a massive cowhide bag which he deposited on a chair as a preliminary to taking off his hat and wiping his forehead. He was a big burly, heavy-browed man, sparing of
