“He left this lamp burning in order to make people believe that he was at work.” And then he added, softly: “There is no sign of a struggle of any sort and in the sand I find the traces of the footprints of only M. Arthur Rance and M. Robert Darzac, who came to this room during the storm last night and have brought on their feet a little earth from the court of the Bold and also of the claylike soil of the outer court. There is no footprint which could be Old Bob’s. Old Bob reached here before and, perhaps, went out while the tempest was raging, but, in any case, he has not come in since.” Rouletabille stood erect. He replaced upon the desk the lamp the rays of which fell directly upon the skull which had been splashed by the red paint in a frightful fashion. Around us there were dozens of skeletons but certainly their presence was less alarming to me than the absence of Old Bob. Rouletabille stood for a moment staring at the crimson skull, then he took it in his hands and held his eyes close to its empty orbits. Then he raised the skull higher and held it at arms’ length, gazing at it with an almost breathless interest; he looked at the profile. Then he placed the hideous object in my hands and told me to raise it to the level of my head, as carefully as thought it were the most precious of burdens while Rouletabille brought the lamp very close to it. Like a flash an idea pierced through my brain. I let the skull fall on the desk and rushed through the court till I came to the oubliette. I discovered that the iron bars which closed it were still fast. If anyone had fled by that way or had fallen into the shaft or had thrown himself down, the bars would have been opened. I hurried back, more anxious than ever. “Rouletabille! Rouletabille! There is no way that Old Bob could have gotten out except in the sack!” I repeated the sentence, but my friend was not listening and I was surprised to see him deeply engrossed in a task of which I found it impossible to guess the meaning. How, at a time as tragic as the present, while we were awaiting only the return of M. Darzac to complete the circle in which the impossible body was found--while in the Square Tower, the Lady in Black, like Lady MacBeth, must be occupied in effacing from her hands the stains of the strangest of crimes, Rouletabille seemed to be amusing himself by making drawings with a foot rule, a square, a measure and a compass. There he was, seated in the old geologist’s easy chair with Robert Darzac’s drawing board before him and he also was making a plan--quiet and imperturbable as an architect’s clerk.