There were iron railings in front of the house, and before the door was a big stone portico. My hands told me both these details. I turned to the left, and after walking some little distance crossed a road and kept on down a long road which, although it did not appear to be a main thoroughfare, seemed to run straight as an arrow. For fully a quarter of an hour I walked on without meeting a soul. The only noise that broke the quiet was the dismal howl of a dog, and now and then the distant shriek and low roar of trains. Suddenly I found myself in quite a labyrinth of crooked streets, and after several turns emerged into what I presumed to be one of the great arteries of London. I stood listening. The air was fresh, and it seemed to me that dawn was spreading. Afar I could hear the measured, heavy tread of a police-constable, and hurried in his direction. As I did so I put out my stick and it struck some iron railings. A few minutes later, in hot haste, I overtook the man of heavy tread, and addressing him, said-- "Tell me, please, are you a constable?" "Well, I believe I am," answered a rough voice, pleasantly withal. "But can't you see?" "No, unfortunately I can't," I replied. "Where am I?" "Outside the South Kensington Museum. Where do you want to go?" "I want you to come with me," I said. "With you. What's up?" "I've been present at a terrible tragedy," I blurted forth. "Two people have been murdered." "Two people?" exclaimed the voice, quickly interested. "Where?" "In--in a house," I faltered, for not until that instant did the appalling truth occur to me. I had wandered away from the place, and had no idea of its outward appearance, or in what road it was situated! "Well, double murders don't often take place in the street, sonny. But--" and the voice hesitated. "Why, there's blood on your clothes, I see! Tell me all about it. Where's the house?" "I confess that I've been foolishly stupid, for I've left it, and I could never find my way back again. I'm blind, you see, and I've no idea of its exterior appearance." "At any rate you've been near enough to the affair to get yourself in a pretty mess," the rough voice said, somewhat suspiciously. "Surely you have some idea of where the affair took place?" The situation was certainly the most curious in which any man could be placed, for with only one thought in my mind, namely, to raise the alarm, I had gone forth from the house of mystery and failed to mark it. This negligence of mine might, I reflected, result in the affair being hushed up for ever. London is a big place in which to search for the scene of a murder upon which my eyes had never gazed, and the details of which I only knew by my sense of touch. How many thousands of houses there were in the West End each with its smoke-blackened portico and little piece of area railing.