It is the rough argillaceous sandstone that accompanies the coal-measures in this part of Wales, and a moderate force gives it quite a rocking motion, which can be easily continued with one hand. It stands nearly in equilibrium upon a pivotal rock beneath. Two miles from Cardiff is the ancient and straggling village of Llandaff, which was the seat of the earliest Christian bishopric in Wales, having been founded in the fourth century. Its cathedral, for a long time dilapidated, has within a few years been thoroughly restored. All the valleys in the hilly region tributary to Cardiff are full of coal and iron, the mining and smelting of which have made enormous fortunes for their owners and developed a vast industry there within the present century. About nine miles north of Cardiff is Caerphilly Castle, which has the most remarkable leaning tower in Britain, it being more inclined from the perpendicular than any other that is known. It is about eighty feet high, and leans over a distance of eleven feet. It rests only on a part of its southern side, and maintains its position chiefly through the strength of the cement. This castle was built by the De Clares in the reign of Henry III., and large additions were made to it by Hugh Despenser, who garrisoned it for Edward II. in order to check the Welsh. It is a large concentric castle, covering about thirty acres, having three distinct wards, seven gate-houses, and thirty portcullises. It was here that Edward II. and his favorites, the Despensers, were besieged by the queen in 1326. The defence was well conducted, and the besiegers were greatly annoyed by melted metal thrown down on them from the walls, which was heated in furnaces still remaining at the foot of the tower. They made a desperate assault, which was partially successful, though it ultimately failed; and we are told that while in the castle they let the red-hot metal run out of the furnaces, and, throwing water on it from the moat, caused an explosion which tore the tower from its foundations and left it in its present condition. The fissures made by the explosion are still visible, and it has stood thus for over five centuries. The castle ultimately surrendered, the king having previously escaped. The Despensers were beheaded, and their castle never regained its ancient splendor. SWANSEA. [Illustration: NORTH DOCK, SWANSEA.]