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 33° N., 93° E., at an altitude of 16,700 ft. above sea-level. Throughout the greater part of its course in Tibet, where it is called the Dza-Chu, it flows south-eastwards to Chiamdo, on the great east and west caravan route from China to Lhasa. At this point it is about 10,000 ft. above sea-level. From here it flows southwards through little-known mountain wastes. Below Dayul in lat. 29° it is known by the Chinese name of Lantsan Kiang. For the next 300 m. of its course the Lantsan Kiang, or, as it soon becomes known among the Thai peoples inhabiting its rugged valley, the Mekong, is very little known to us. The river flows beneath bare and rocky walls. A few scattered villages of Lusus and Mossos exist in this region; there is no trade from north to south. In 25° 18′ N. the Tali-Bhamo caravan route, described by Colborne Baker, crosses the river by one of those iron suspension bridges which are a feature of Yun-nan, at a height of 4700 ft. above sea-level. From this point to Chieng or Keng Hung, the head of the old confederacy of the Sibsawng Punna or Twelve States, it is little known; the fact that it falls some 900 ft. for each degree of latitude indicates the character of the river. Under the provisions of the Anglo-French agreement of January 1896, from the Chinese frontier southwards to the mouth of the Nam Hok the Mekong forms the frontier between the British Shan States on the west and the territories acquired from Siam by France in 1893. By the treaty of 1893, from that point southwards to about 13° 30′ N. it is also the frontier between French Indo-China and Siam, and a zone extended 25 kilometres inland from the right bank, within which the Siamese government agreed not to construct any fortified port or maintain any armed force. This 25 kilometre neutral zone was abolished in 1905 when France surrendered Chantabun to the Siamese, who in their turn ceded the port of Krat and the provinces of Melupre and Bassac, together with various trading concessions to France on the right bank of the Mekong. Below the Siamese Shan town of Chieng Sen the river takes its first great easterly bend to Luang Prabang, being joined by some important tributaries. This portion is obstructed by rapids. The country is mountainous, and the vegetation of the lower heights begins to assume a tropical aspect. From Luang Prabang the river cuts its way southwards for two degrees through a lonely jungle country among receding hills of low elevation. From Chieng Khan the river again turns eastwards along the 18th parallel, forcing its way through its most serious rapid-barrier, and receiving some important tributaries from the highlands of Tung Chieng Kum and Chieng Kwang, the finest country in Indo-China. In 104° E. the river resumes a southerly course through a country thinly peopled. At Kemarat (16° N.) the fourth serious rapid-barrier occurs, some 60 m. in length, and the last at Khong in 14° N. From here to its outfall in the China Sea the river winds for some 400 m. through the French territories of Cambodia and Cochin China, and to its annual overflow these countries owe their extraordinary fertility. The French have done much to render the river navigable. Steamers ply regularly from Saigon through Mytho to Pnompenh, and launches proceed from this place, the capital of Cambodia, to the Preapatano rapids, and beyond this a considerable portion of the distance to Luang Prabang, the journey being finished in native boats.

 MELA, POMPONIUS (fl. c. 43), the earliest Roman geographer. His little work (De situ orbis libri III.) is a mere compendium, occupying less than one hundred pages of ordinary print, dry in style and deficient in method, but of pure Latinity, and occasionally relieved by pleasing word-pictures. Excepting the geographical parts of Pliny’s Historia naturalis (where Mela is cited as an important authority) the De situ orbis is the only formal treatise on the subject in classical Latin. Nothing is known of the author except his name and birthplace—the small town of Tingentera or Cingentera in southern Spain, on Algeciras Bay (Mela ii. 6, § 96; but the text is here corrupt). The date of his writing may be approximately fixed by his allusion (iii. 6 § 49) to a proposed British expedition of the reigning emperor, almost certainly that of Claudius in 43. That this passage cannot refer to Julius Caesar is proved by several references to events of Augustus’s reign, especially to certain new names given to Spanish towns. Mela has been without probability identified by some with L. Annaeus Mela of Corduba, son of Seneca the rhetorician, and brother of the great Seneca.

MELACONITE, a mineral consisting of cupric oxide, CuO, and known also as black copper ore. In appearance it is strikingly different from (q.v.) or red copper ore, which is cuprous oxide. Crystals are rare; they belong to the monoclinic, or possibly to the anorthic system, and have the form of thin triangular or hexagonal scales with a steel-grey colour and brilliant metallic lustre. More often the mineral is massive, earthy or pulverulent, and has a dull iron-black colour. Hence the name melaconite, from the Greek , black and  , dust, which was originally given by F. S. Beudant in 1832 in the form melaconise. The crystallized Vesuvian mineral was later named tenorite, a name commonly adopted for the species. The hardness of the crystals is 3–4, but the earthy and powdery forms readily soil the fingers; the spec. grav. is 5·9. Crystals have been found only at Mt Vesuvius, where they encrust lava, and in Cornwall. The other forms of the mineral, however, are common in copper mines, and have resulted by the alteration of chalcocite, chalcopyrite and other copper ores, on which they often form a superficial coating.

 MELAMPUS, in Greek legend, a celebrated seer and physician, son of Amythaon and Eidomene, brother of Bias, mythical eponymous hero of the family of the Melampodidae. Two young serpents, whose life he had saved, licked his ears while he slept, and from that time he understood the language of birds and beasts. In the art of divination he received instruction from Apollo himself. To gain the consent of Neleus, king of Pylos, to the marriage of his daughter Pero with Bias, Melampus