SIAL'OGOGUES are substances which, by local stimulating action, increase the secre tion of saliva. Among the substances which thus act as direct stimulants to the sali vary glands (q.v.). we may especially mention horse-radish root, mezereon bark, and pellitory root. Horse-radish root when chewed, produces a copious flow of saliva, and has been found useful in aiding deglutition in cases of paralysis of the tongue. If mezereon bark is used in the same way, the saliva should be frequently ejected, in con sequence of the acrid properties which it absorbs from the drug. Pellitory root is the best of this class of remedies. Fragments weighing from half a dram to a dram may be frequently.che•ed when we wish to increase the flow of saliva in cases of facial neuralgia, rheumatism of the muscles of mastication, and paralysis of the tongue.
SIAM' (native name Thdi = the free, or Mang Thdi= the kingdom of the free), the chief state of Indo-China, is bounded on the s. by the gulf of Siam and the Malay pen insula. On the w., n., and e., the frontier-line is ill-defined and fluctuating, owing to many tribes being only partially under subjection, and to the constant wars of aggran dizement between Siam and the Malayan and Burmese races on the w., and the Cambo dian and Cochin-Chinese races on the east. According to a recent account, the country lies in lat. 4° to 21° n., long. 96° to 102° c.: is 1200 m. in length, and about 350 nu. iu extreme breadth. Area estimated at from 190,000 to 290,000 sq.m.; pop. stated at from 6,000,000 to 10.000.000. The kingdom consists of 41 provinces, each governed by a phraya, or functionary of the highest rank. There are numerous districts Leyond the limits of the kingdom proper, as the Laos, Malayan, and Cambodian dependencies, which are more or less under subjection to Siam, and pay tribute generally once in three years. Siam itself pays tribute to China, but only as a matter of usage and convenience, for it receives from that country more than a return, in'the remission of duties upon Siamese vessels bound to Chinese ports. Cambodia is situated between Siam on the w. and Cochin-China, and as sovereignty over it is claimed by both these countries, and as it is too feeble to resist the claims, it pays tribute to both.
SuVace, Ilydrography, ast-tine, Sail, and Climate.—The mountains which cover the' northern districts of the country, and form natural barriers along its e. and iv. frontiers, are branches of the great system of the Himalaya. Though the northern dependencies of Siam are mountainous, the kingdom proper is a vast plain, which only bet:mitts hilly on its northern frontier.' The great river of the country, the Nile of Siam, is called by foreigners Menatn, or more commonly Meinam; but the Siamese call all rivers by this name, and distinguish the river by adding to the name Mccani the mane of the chief town or village on its banks; thus Menam Bangkok is the river of Bangkok, that is, the great river of the country, which Europeans and other foreigners have agreed to call Meinam.- This river, the great life-sustaining artery of the country, rises among the
mountains of the Chinesa province of Yunnan, whence it flows s., and after a course of more than 800 in. in this direction, throws itself by three mouths, which arc from 6 to 8 fathoms deep, into the gulf of Siam, about 30 m. (18 m. in direct line) below Bangkok. •It receives a number of important affluents, notably the ricer Phitsalok, which joins it in lat. about 17° 35' n. The annual inundation of the Meinam, the occasional non occurrence of which entails failure cu a great portion of the rice crops, commences in June and ends in November. Impregnated with the rich soil which it brings. from the interior, its waters in August overflow the hanks to a height sometimeg exceeding 6 fk above the ordinary level. The tract of country within the direct influence of the inan dations is estimated at 12,000 sq.m.; but, properly speaking, the actual valley of the Meinam, commenting 450 m. above the mouth of that river, and with an average breadth of 50 in., has an area of upward of 22,000 sq.m., and forms a tract or country the fertility of which is not exceeded in any other quarter of the globe. Of the other great rivers, the chief is the Mei-kong, which flows threugh the eastern districts of the empire, end is said to be 1600 m. long. The coast-lice fringing the edge of the gulf of Siam may be roughly estimated at 1100 m., exclusive of minor windings. The principal ports on the coastline are Paknam (pop. 6,500), defended by three forts; Paklat, a ft w miles above Paknam (pop. 7,000), defended by a fort on each side of the river; Meklong, at the mouth of the river of the same name, long. 1CO° 10' e., a beautiful city, with floating bazaars, fine pagodas and gardens, and a p. of 10.000; Chantaburi, long. about 108° e., near the mouth of a river which, though F11011, fertilizes with its inundations a consider able district, a place of active trade with China and Cochin-China, with a pop. of 6,000; and 27 m. e.s.e. of Paknam, engaged in a profitable fishery and in agriculture, pop. 6,000. The breadth of the Malayan peninsula, in tat. 11° n., is only 50 m., and here two streams, the one flowing w. to the bay of Bengal, and the other e. to the gulf of Siam, otter great facilities for the construction of a ship-cant*, for their sources being near each other, a few miles of canalization are all that would be required to connect them, and thus form a sea-way across the peninsula, which would shorten the voyage between India and eastern Asia by many days, and often by weaks.—The climate of Siam is. for a tropical region, salubrious; the resident missionaries speak highly in its favor. The mean temperature at Bangkok for a series of eight years was 81° 14'; the maximum heat within the same space was 97', and the minimum 54°. Hurricanes and typhoons are almost unknown is Siam, though it is visited every year by the s.w. and n e. monsoons—the former bringing clouds, thunder-storms, alio rain,the latter bringing refreshing weather.