Fergusson’s opinion, that this shrine was devoted to the worship of the snake god (see _Tree and Serpent Worship_), is not in accord with the views of Garnier, Thomson and others, who agree that it must have been erected in honor of Buddha. Dr. Bastian, president of the Berlin Geographical Society, thinks, with Bishop Pallegoix, that the probable date of the building――at least its commencement――was the grand event from which the civil era of Siam dates――viz. the introduction of the sacred Buddhist canon from Ceylon in the seventh century. The general appearance of the worn stairways, and the dilapidated condition of the city, slowly mouldering under the destructive encroachments of a tropical jungle, would seem to indicate great age. Yet the mediæval narrative of Cambodian travel by a Chinese officer, late in the thirteenth century, recently translated by M. Remusat, contains no allusion to this great temple, which has induced some to conclude that the building belongs to a later period. In 1570 A. D. a Portuguese refugee from Japan refers to these “ruins” and the inscriptions thereon as being in “an unknown tongue.” III. THE THIRD BASIN――VALLEY OF THE MEKONG. The hill-country which separates the valley of Siam from that of the Mekong (or Mekaung)――known in its lower course as the Cambodian River――is of moderate elevation and the boundary-lines not well defined. The Mekong is one of the most remarkable streams of Asia. It rises in Thibet, passes through Western Yunnan parallel with the Yangtse and Salween, till, breaking through the mountains not far from each other, the Yangtse flows across China and the Salween to the Bay of Bengal, while the Mekong, crossing Laos and Cambodia, after a somewhat devious course of at least two thousand miles reaches the Cochin-China delta. The broken character of the Laos country gives the Mekong in its rapid descent from plateau to plateau during its upper course the velocity of a mountain-torrent as it tears along, with a noise like the roaring of the sea, through deep gorges overshadowed by rocky defiles. In Upper Laos the river is from six to eight hundred feet wide, and has in the dry season an average depth of twenty feet, while the banks are some twenty-five feet above the water, the difference between the ordinary height and floodmark being very great. The rainy season begins in April with the melting snow; the water rises gradually from that time to July or August, when the country is flooded.