In the manufacture of glass and crystal it plays an important part, as it forms one of the chief ingredients of flint-glass and crown-glass, of which, as is well known, the achromatic lenses are made which have so wonderfully improved the distinctness of our telescopes. United with tin it forms an alloy which is more fusible than either metal alone, and which is consequently used as a solder by the plumbers, while with antimony it combines into a hard mass which serves to make letters for the printing-press. All these various uses absorb immense quantities of lead, and render it one of the most valuable products of the subterranean world. Among the lead mines of Europe we find the first rank occupied by those of Spain, which in 1863 furnished the enormous mass of 309,940 tons of galena. The principal mines are situated in Guipuzcoa, Catalonia, Arragon, the Sierra Morena, and, above all, in the mountain chain of the Alpujarras, where the rocks of the Sierra Gador are everywhere traversed by veins of galena. The production of North Germany is also very considerable. In 1865 Prussia furnished 57,808 tons of galena, and the Hanoverian Hartz Mountains, which produced 101,411 tons in 1864, and now belong to the same monarchy, have raised its previous production to a threefold amount. The chief lead mines of England are situated near Alston Moor, where the three counties of Northumberland, Durham, and Cumberland meet together. The lofty hills of the district, bare of wood and almost wholly covered with marshy heaths, are intersected by the valleys through which run the Tyne, the Wear, and the Tees, with their numerous branches. The country, though little frequented by tourists, is wild and picturesque; but the deep gorges with which it is furrowed have more than a mere romantic interest, for they lay open to view numerous veins of ore, and direct the operations of the miner to the places where it is sufficiently abundant to reward his toil. The town of Alston, the mining centre of the district, is beautifully situated close to the river Tyne, which, about five miles above it, ascends, between lofty hills, to the foot of Cross Fell, this picturesque mountain giving a character of considerable grandeur to the surrounding scenery. The mines of the Alston Moor district produce annually about 25,000 tons of lead. The waters are drawn off by long adit levels, and the ores are dragged out by horses to the day. This region extends southward to the Yorkshire valleys of Swaledale, Arkendale, and to Grassington, where numerous lead mines are worked under very similar circumstances. The Yorkshire mines yielded in 1856 8,986 tons of lead.