As to how we spent our time during the afternoon, all I need say is that Rouletabille led me to the grotto of Sainte-Geneviève, and, all the time, talked of every subject but the one with which we were most interested. Towards evening I was surprised to find Rouletabille making none of the preparations I had expected him to make. I spoke to him about it when night had come on, and we were once more in his room. He replied that all his arrangements had already been made, and this time the murderer would not get away from him. I expressed some doubt on this, reminding him of his disappearance in the gallery, and suggested that the same phenomenon might occur again. He answered that he hoped it would. He desired nothing more. I did not insist, knowing by experience how useless that would have been. He told me that, with the help of the concierges, the château had since early dawn, been watched in such a way that nobody could approach it without his knowing it, and that he had no concern for those who might have left it and remained without. It was then six o’clock by his watch. Rising, he made a sign to me to follow him, and, without in the least trying to conceal his movements or the sound of his footsteps, he led me through the gallery. We reached the “right” gallery and came to the landing-place which we crossed. We then continued our way in the gallery of the left wing, passing Professor Stangerson’s apartment. At the far end of the gallery, before coming to the donjon, is the room occupied by Arthur Rance. We knew that, because we had seen him at the window looking on to the court. The door of the room opens on to the end of the gallery, exactly facing the east window, at the extremity of the “right” gallery, where Rouletabille had placed Daddy Jacques, and commands an uninterrupted view of the gallery from end to end of the château. “That ‘off-turning’ gallery,” said Rouletabille, “I reserve for myself; when I tell you you’ll come and take your place here.” And he made me enter a little dark, triangular closet built in a bend of the wall, to the left of the door of Arthur Rance’s room. From this recess I could see all that occurred in the gallery as well as if I had been standing in front of Arthur Rance’s door, and I could watch that door, too. The door of the closet, which was to be my place of observation, was fitted with panels of transparent glass. In the gallery, where all the lamps had been lit, it was quite light. In the closet, however, it was quite dark. It was a splendid place from which to observe and remain unobserved.