Upon the reading of this letter I made sure my colleague was insane; but till that was proved beyond the possibility of doubt, I felt bound to do as he requested. The less I understood of this farrago, the less I was in a position to judge of its importance; and an appeal so worded could not be set aside without a grave responsibility. I rose accordingly from table, got into a hansom, and drove straight to Jekyll's house. The butler was awaiting my arrival; he had received by the same post as mine a registered letter of instruction, and had sent at once for a locksmith and a carpenter. The tradesmen came while we were yet speaking; and we moved in a body to old Dr. Denman's surgical theatre, from which (as you are doubtless aware) Jekyll's private cabinet is most conveniently entered. The door was very strong, the lock excellent; the carpenter avowed he would have great trouble and have to do much damage, if force were to be used; and the locksmith was near despair. But this last was a handy fellow, and after two hours' work the door stood open. The press marked E was unlocked; and I took out the drawer, had it filled up with straw and tied in a sheet, and returned with it to Cavendish Square. Here I proceeded to examine its contents. The powders were neatly enough made up, but not with the nicety of the dispensing chemist; so that it was plain they were of Jekyll's private manufacture; and when I opened one of the wrappers, I found what seemed to me a simple, crystalline salt of a white colour. The phial, to which I next turned my attention, might have been about half-full of a blood-red liquor, which was highly pungent to the sense of smell and seemed to me to contain phosphorus and some volatile ether. At the other ingredients I could make no guess. The book was an ordinary version-book, and contained little but a series of dates. These covered a period of many years, but I observed that the entries ceased nearly a year ago, and quite abruptly. Here and there a brief remark was appended to a date, usually no more than a single word: "double" occurring perhaps six times in a total of several hundred entries; and once very early in the list, and followed by several marks of exclamation, "total failure!!!" All this, though it whetted my curiosity, told me little that was definite. Here was a phial of some tincture, a paper of some salt, and a record of a series of experiments that had led (like too many of Jekyll's investigations) to no end of practical usefulness. How could the presence of these articles in my house affect either the honour, the sanity, or the life of my flighty colleague? If his messenger could go to one place, why could he not go to another? And even granting some impediment, why was this gentleman to be received by me in secret? The more I reflected, the more convinced I grew that I was dealing with a case of cerebral disease; and though I dismissed my servants to bed, I loaded an old revolver that I might be