This iron door led from the bridge into the library, and from the tower into a large vaulted hall with a pillar in the centre. As already stated, this hall was in the second story of the keep. Like the tower itself, it was circular in its form, and was lighted by deep embrasures overlooking the fields. The stones of its rough and naked walls, unhidden from the view, were, however, symmetrically adjusted. This hall was reached by a spiral staircase built in the wall,--quite a simple matter when walls are fifteen feet thick. In the Middle Ages they used to capture a city by streets, a street by houses, and a house by rooms; and thus a fortress was besieged story by story. In this respect La Tourgue was very skilfully arranged, and very difficult to cope with. An uncomfortable staircase connected one story with another; the doors were sloping, and not high enough to admit a man unless he bent his head; and where at every door the besieged stood in waiting for their assailants, a bowed head was certain death. Below the circular hall with the pillar were two similar rooms, composing the first story and the ground-floor, and above these three more. The tower was closed, so to speak, by a platform which rested on these six rooms like a stone cover, and a narrow watch-tower led up to the platform. As they were obliged to pierce this wall in which the iron door was sealed to a depth of fifteen feet, it was thereby framed in a deep archway, which when the door was closed formed a porch six or seven feet deep, towards the bridge as well as towards the tower, and when it was open these two porches united to form the entrance arch. Set in the wall under the porch, towards the bridge, was a low gate with a Saint-Gilles bolt, leading into the corridor of the first story under the library. This was another difficulty for the besiegers. That side of the castle on the bridge looking towards the plateau ended in a perpendicular wall, and there the bridge was severed. The drawbridge set up against a low gate to connect it with the plateau, and which on account of the height of the latter could only be lowered like an inclined plane, led into the long corridor called the guard-room. The besiegers who found themselves in possession of this corridor would have been obliged to carry by main force the Saint-Gilles winding stairway that led to the second story, in order to reach the iron gate. VI. THE LIBRARY.