MENAM, or Me Nam (literally the “mother water” or “main river”), a river of Siam, the chief highway of the interior, on whose yearly rise and fall depends the rice crop of Lower Siam. Rising in the Lao or Siamese Shan state of Nan, at a height of 1400 ft. upon the shoulders of the mountain mass of Doi Luang, it is first known as the Nam Ngob, after a village of that name. As the Nam Nan, still a mountain stream, it flows southward through the state so named between high forested ranges, and, notwithstanding the frequent rapids along its course, the natives use it in dug-outs for the transport of hill produce. From Utaradit, where it leaves the hills of the Lao country, it flows southward through the plain of Lower Siam, and is navigable for flat-bottomed native craft of considerable capacity. It is here known as the Nam, or Menam Pichai. Below Pichai the river flows through forest and swamp, the latter providing vast overflow basins for the yearly floods. Thousands of tons of fish are caught and cured here during the fall of the river after the rains. Below Pitsunalok the waters of the Menam Yom, the historic river of Siam, upon which two of its ancient capitals, Sawankalok and Sukotai, were situated, meander by more than one tortuous clayey channel to the main river, and combine to form the Nam Po. At Paknam Po the main western tributary comes in, the shallow Me Ping, the river of Raheng and Chieng Mai, bringing with it the waters of the Me Wang. As the chief duty-station for teak, which is floated in large quantities down all the upper branches of the river and as a place of transshipment for boats, Paknam Po is an important and growing town. From this point southwards the river winds by many channels through the richest and most densely populated portion of Siam. About Chainat the Tachin branches off, forming the main western branch of the Menam, and falling into the gulf at a point about 24 m. west of the bar of the main or Bangkok river. At Ayuthia, another of the ancient capitals of Siam, the Nam Sak flows in from the north-east, an important stream affording communication with the rich tobacco district of Pechabun, and draining the western slopes of the Korat escarpment.