"Given the hypothesis that Miller was murdered, the rest was easy. If you will go back there, Brasher, and dig your nail into the putty holding the window nearest to the bolt, you will find it soft; the other putty is hard. There are five rows of panes. The one I refer to is in the middle row at the extreme left. The killer had the forethought to use putty that was of about the same color as old putty. But I saw on the sill some minute grains of glass glinting in the light. "Mrs. Horsnall, without knowing why I asked the question assured me that there had been no repairs, such as replacing panes of glass. When I leaned out of the window, I saw the scars in the cement. Perfectly obvious. An active man, a strong man, probably a left-handed man, threw a string with a stone at the end over Miller's Folly. With this string he drew over the building a stronger twine. Finally he drew over the top of the building a strong rope, like a wash line, or something stronger. He then drew both ends of the rope around, forming a loop, about the chimney. "Using the chimney as his anchor, with his rope looped around it, it was fairly easy for an active man. He used the kind of spurs that electric workers use to climb up wooden poles. Those spurs left the scars I pointed out. He had a hand hold, of course, on the two ends of the rope hanging from the chimney about two feet from the window. "The rest was rather difficult. When he reached the height of the window, the nearest pane, fortunately for him, the one near the bolt was two feet from his perch, at his left. That is why I suggest that he may be a left-handed man. He cut out the pane, opened the window, went in, killed Miller and then spent some time hiding his traces. Among these was replacing a pane of glass and using putty colored like old putty. "A very, very dangerous murderer and a very clever one, but hardly a subtle one." He turned to Brasher. "Now, young man, the rest ought to be simple police work. Find a man in possession of twine and rope, on which you will find adhering bits of brick, cement and paint, from Miller's roof. Find him in possession of a pair of spurs, on which you may find adhering bits of cement and you have your murderer." As Brasher, thanking him effusively, was about to go. Professor Brierly detained him. "Just a moment. I want to send a telegram to New York. Leave this at the telegraph office for me, please." He turned to his companions as Brasher departed; he smiled whimsically: "Since you insist on plunging me into these things, I might as well be prepared. I wired for several things that we may need before this is over." McCall was knitting his brow. He had followed with glowing admiration the exposition of the old savant. "Professor," he asked, "you say the murderer is a clever one, but hardly a subtle one. Why do you say that?"