"Yes, Professor, it does, but one of the peculiarities about this kind of thing is that it destroys its own evidence pretty much. If we don't know where the lighted fuse originated and where it led, it doesn't do us much good, does it?" "That's right, but this obviously comes from an upper room, doesn't it?" "Yes, I believe it does. But the upper rooms are gone, you see." "And you really think, do you Mr. Hall, that there was a timing device? It seems plausible to you that men who are engaged in such desperate business would leave such a thing to the mere chance of finding their victim home at the time their device was set to go off?" "Well, perhaps not, Professor, but what else is there?" "Nothing, yet, Mr. Hall, but let us look about." Professor Brierly, with Jimmy and Matthews close at his heels, went picking his way through the wreckage. He stepped outside and looked carefully among the debris. The force of the explosion seemed to have propelled a major portion of the wreckage in the direction of the backyard. It was here that Professor Brierly found a section of a papered wall with a telephone bell-box attached. He looked long and earnestly at a spot of the paper near what had been the bottom of the box. With Matthews' help, he forced open the enameled lid, exposing the wires, binding posts, terminals and bell. From among the wires he carefully picked out a frayed piece of gray thread. He once more peered intently into the box and at the papered area of wall to which it was attached. "John," he said, holding the thread up for the young man's inspection. "Does this properly belong to a telephone box of this type?" Matthews looked curiously at the bit of frayed thread. He shook his head. "I can't understand what it's doing there, Professor." "And yet, John, this bit of thread had a very definite function, a very definite and murderous function, indeed. I think I am beginning to understand. Now let us go look for a timing device." "But you said there wasn't any timing device, Professor," protested Jimmy. "At any rate," answering the old man's glare, "that it appeared illogical that a timing device was employed." "Nevertheless, Mr. Hale, there was a timing device, not the kind Mr. Hall had in mind, perhaps, but some timing device. The explosion you will admit was timed very accurately indeed." He walked outside, followed by his two companions. He walked briskly toward the patch of woods. Here he entered a faint path that was evidently used by those who came to this street from the state road. He walked carefully along the edge of the woods skirting the road on which was the wrecked house. A few yards from the path he came to a cleared patch. He stopped and looked about him. He pointed to the ground. He said: