Between these two buildings there was no harmony whatsoever; the roughness of the one jarred against the elegance of the other. It would seem as if two semicircles ought to be identical; yet no two styles have less in common than that of a Roman semicircle and a classic archivolt. That tower, a worthy companion for the forest, was a strange neighbor for the bridge, which might have come from Versailles. Fancy Louis XIV. leaning on the arm of Alain Barbe-Torte. There was something appalling in this juxtaposition. An inexpressible spirit of terror pervaded the combined majesty of these structures. Let us repeat, that from a military point of view the bridge went far towards betraying the tower; for while it added to its beauty it diminished its strength, ornamenting it on the one hand and weakening it on the other; by placing it on a level with the plateau, it had exposed it to attacks from that direction, although it still remained impregnable in the direction of the forest. Formerly it had commanded the plateau, but matters were now reversed. An enemy installed on the plain would speedily become master of the bridge. The library and the granary were advantageous to the besiegers rather than to the besieged, since the contents of both are of a combustible nature. For an assailant who knows how to avail himself of fire as a means of assault, it matters but little whether it be a Homer or a bundle of hay, provided it burns. The French offered a proof of this fact to the Germans when they burned the library at Heidelberg, as did the Germans in burning that of Strasbourg. In short, this bridge built on to the Tourgue was a strategic mistake; but in the seventeenth century, under Colbert and Louvois, the Princes Gauvain, like the Princes de Rohan or La Tremoille, believed themselves henceforth safe from assault. Still, the builders of the bridge had taken certain precautions. In the first place, anticipating the chances of fire, they had fastened crosswise below the three windows looking towards the stream, by iron clamps which no longer than fifty years ago were still to be seen, a strong ladder, equal in length to the height of the first two stories of the bridge,--a height surpassing that of three ordinary stories; secondly, foreseeing the possibility of a siege, they had isolated the bridge from the tower by means of a low and heavy iron door, arched at the top and locked with a large key, whose hiding-place was known to the master alone; once closed, it could defy the battering-ram and almost brave the cannon-ball. One must cross the bridge to reach this door, which was the only means of access to the tower. V. THE IRON DOOR. As a result of the elevation of this castle on the bridge by means of piles, its second story was on a level with the corresponding story of the tower; and here, for greater safety, the iron door had been placed.