The Professor, after a glance round the room, perceived the helplessness of his position. The man was clearly mad, but his mania was strictly limited. Upon most subjects he was sane as he was himself. He must perforce listen to what he had to say. Perhaps, during the time which this would occupy, he might be able to evolve a scheme for his capture. He walked across the room and sat down in the chair which the Black Sailor pointed out to him. The man immediately took the chair opposite. “Artists are naturally vain, Dr. Priestley,” he began, “and I think my exploits entitle me to consider myself an artist. I have long promised myself the pleasure of recounting them to one who would appreciate their ingenuity, and you are the very man for such a purpose. I have, I believe, read everything that you have written, and I have understood a nature which revels in ingenious methods. I flatter myself that what I have to tell you will, at least, not bore you.” “I shall be extremely interested to hear it,” replied the Professor quietly. “Before Dr. Morlandson died, he furnished me with a list of his intended victims, and a very fine collection of lethal apparatus,” continued the Black Sailor. “My first concern was to find some spot in London from which to operate. I made careful enquiries as to the present addresses of the surviving jurymen, and found that most of them came from this part of London. This, of course, was not Coincidence, since juries are frequently called by districts. “I therefore determined to establish myself in this neighbourhood. I knew enough of the properties of herbs to set myself up as a herbalist, and I was fortunate enough to find this empty shop, almost opposite the premises of one of my intended victims. Once in possession of it, I set myself to develop a business which should bring me into contact with all the gossip of the neighbourhood, and to study the habits and circumstances of my intended victims. My own apparent vocation I tried to make as open as I could. My shop was available to any who cared to enter it, and from the first I accustomed the acquaintances which I made to my habit of spending occasional week-ends in the country, and of taking a walk every evening, since I foresaw that these would be essential to my purpose. And in Mr. Copperdock I found a simple and not over-intelligent personality who would serve me admirably as a dupe upon whom suspicion might be cast. “You will, I think, understand the task which I had been set. I was to execute the vengeance of Dr. Morlandson upon the men who had condemned him to so many years of agony. But this must be done in such a manner that their deaths would not be attributed to pure chance, but must eventually be made to appear as acts of justice, as indeed they were. I could not employ the same methods in each case, but at the same time I wished each death to carry the same distinguishing mark.