Meanwhile we glide on through dreary regions, the far distance bounded by barren mountains. We pass over vast treeless plains strewn in all directions, as far as the horizon, with huge broken masses and boulders of granite. A scene more expressive of gloom and desolation cannot be imagined. The huge fragments, scattered about as far as the eye can reach, are piled up occasionally into enormous heaps, which look like the remains of ruined cities of an unknown age; or spread widely over the grey expanse, like the tombs of the races which once inhabited these regions. It is impossible, indeed, to conceive anything more austere than the effect produced by a scene at once so grand and so desolate. The railroad now began to ascend by gradual inclines, making wide casts over the stony tracts. The amount of engineering skill, money, patience, and gunpowder it must have taken to cut through, in some places, miles of solid granite, must have been great. We were now commencing the ascent of the Guadarrama Mountains, which overlook from afar the capital of Spain. This fine _ferrocarril_, the construction of which is somewhat similar to that of the railroad over the Sömmering Pass near Trieste, surmounts altitudes by curves and gradual inclines. The Guadarrama Mountains, with other sierras, of which the principal are the Somo Sierra, the Sierra Morena, the Alpuxarras, the Sierra Nevada, and the Sierra de Ronda, are remarkable features in the aspect of Spain. Surrounding the plains of Castile and La Mancha, the highest of such extent in Europe, with strong natural bulwarks, they are invaluable to the Spaniard in the defence of his native land. They even seem to constitute distinct moral divisions of the inhabitants. The whole country thus appears to be formed of several intrenched camps, and is admirably adapted for a war of posts--particularly for guerilla warfare, by their skill in which the Spanish mountaineers were enabled to offer such a successful resistance to their French invaders.