1911 Encyclopædia Britannica (1911)
“ The basin is comparatively narrow, and the Tagus, like the other rivers of the Iberian tableland, generally flows in a rather confined valley, often at the bottom of a rocky gorge below the general level of the adjacent country. The river rises on the western slope of the Muela de San Juan (5225 ft.) , a mountain which forms part of the Sierra de Albarracin, 88 m. E. of Madrid. Thence the Tagus flows at first north- westwards, but, after receiving the Gallo on the right, it flows west, and then south-west or west-south-west, which is its general direction for the rest of its course. ”
