p15 3. The Pit and the Pendulum by Edgar Allan Poe

He can now see the cell by a sulfurous light and observes that the circumference of the room is only half what he estimated, since he must have nearly circumnavigated the dungeon before falling asleep and then accidentally backtracked the entire circuit after waking up. He also sees that the room is actually square, that the floor is made of the stone, and that the walls are made of large plates of metal and decorated with frightening figures. He can also see the circular pit in the center of the room.