or BADKU, a town, with an adjoining district of the same name, in the Russian province of Daghestan. Badku is the most spacious and convenient port in the Caspian. It stands in the peninsula of Apsaheron, in Long. 49° 40', E. Lat. 40° 22' N. It is a place of considerable trade, and is defended by a double wall and ditch, constructed during the reign of Peter the Great. The town, which is situated on a declivity, is of an obtuse-triangular form, and was a celebrated resort of the ancient worshippers of fire. Before the conquest of the Saracens it was annually visited by thousands of pilgrims, and is still visited by a few Persian fire-worshippers. In the adjacent district a great quantity of excellent cotton is produced, which is exported from Badku; together with fruit, opium, rice, silk, wine, rock-salt, and naphtha. Cloths, dye-stuffs, iron, linen, and silk stuffs, are imported from Astracan, with which place its principal trade is carried on. In the plain nine miles north of the city, enormous quantities of naphtha are produced. It is drawn from wells, some of which yield from 1000 to 1500 lb. in a day; and the district, in dry weather, has often afforded as much as 5600 lb. in one day. The naphtha consists of two kinds, the impure or black, containing petroleum, and the pale yellow or white, which is pure naphtha. The quantity annually obtained in the district amounts to 240,000 Russian poods, or 9,600,000 lb. of the first sort, and 900 poods, or 36,000 lb. of the latter. The fundamental rock of this district appears to be a secondary limestone, on which is imposed a bed of white clay; then two strata of bituminous shale separated by a bed of sand; next a stratum of fossiliferous sandstone, covered by a bed of clay. The naphtha oozes through the fissures of the white clay, and probably is thus distilled by subterranean heat. These wells contain inexhaustible springs of oil; and they are no sooner emptied than the oil begins to flow, and continues until it has attained its former level. It is used by the natives for lamp-oil, and emits a clear light, with much smoke and a disagreeable odour. All around the town the country is deeply impregnated with inflammable matter, both above and below the surface. About 15 miles to the N.E. is a fire temple of the Guebros; a remarkable spot, something less than a mile in circumference, from the centre of which a bluish flame is seen to arise. Here are some small houses; and the inhabitants, when they wish to smother the flame, cover the space inclosed with walls by a thick loam of earth. When an incision is made in the floor, the flame arises; and when it is no longer wanted for culinary or other purposes, it is again suppressed by closing the aperture. The whole country around Badku has at times the appearance of being enveloped in flames. It often appears as if fire rolled down the mountains in large masses with great velocity; and at night a bright blue light is observed to cover the whole western range of hills. This fire does not consume, or emit any sensible warmth.

The jurisdiction of Baku extends over thirty-two villages. It was ceded to Russia in 1723, and restored to Persia in 1735. After remaining for some years under the dominion of Persia, in 1801 it was taken possession of by the Russians, by whom it is still retained. The district, including the town, contains, according to Klaproth, 19,000 inhabitants.