much request for hydraulic structures; for although friable in the quarry, it becomes exceedingly hard under water. 1 Luxembourg. The sandstone of this name (gres lie Luxembourg) is referable to the lower portion of the Jurassic series. On a rock of this sandstone the strong fortress of Luxembourg is built. The red sandstone at Iiommartin (Meurthe) has furnished most of the stone for the churches and buildings of Lorraine, such as those of Saint Wandel and Sarre- briick, remarkable for their rich brown colour. Germany. The New Red Sandstone (Bunter Sand- stein) is much employed for building in some parts of Germany. At Heidelberg it rises into the lofty ridge of the Kaiserstulil, and from the quarries of the vicinity the grand old castle, together with many of the buildings of the town, have been constructed. The stone has a reddish tint, which affords a pleasing contrast to the green of the forests which rise behind the buildings along the banks of the Neckar. The gres de Wurtemberg, belonging to the Bunter Sandstein formation, is quarried in the Black Forest. It is of excellent quality, generally fine grained, and the grains being cemented by silica it is exceedingly durable. Of this stone the beautiful gothic Cathedral of Cologne is chiefly constructed. 1 Chateau, i. 185.