SMOKELESS POWDER. 269 SMOLLETT. Guttmann, The Manufacture of Explosives (Lon- don. 18!>5). SMOKE NUISANCE. Smoke is produced by the incomplete combustion of fuel, tiny bits of unconsunied matter being wafted into the air by the gases which are liberated and not decomposed. In order to eti'eet complete combistion, it is nec- essary that all the constituent gases be raised to a very high temperature and mixed with oxygen before the temperature falls. The difl'erence betweeeu liituminous and anthra- cite coal is that while anthracite is composed of almost pure carbon, bituminous contains in ad- dition to the fixed carbon a compound of carbon and hydrogen, which makes, under present meth- ods, all the trouble. When bituminous coal is ignited these hydrocarbons are first volatilized >y the heat, then the hydrogen unites with the oxygen of the air and the carbon is set free. These free carbon particles are made incandes- cent by the intense heat, and it is this which produces the bright flame so characteristic of bituminous coal. If there is at this stage a sufficient supply of oxj'gen and enough, but not too much, heat, the caAon will be transformed into carbonic acid gas and combustion will be complete. If there is not enough oxygen some of the free particles of carbon will escape through the chimney as smoke. Smoke will also be pro- duced by the "volatilization of the hj'drocarbong at a heat less than that necessary to separate the hydrogen from the carbon; or if, on the other hand, the heat is so suddenly intense that some of the fixed carbon is carried off before it has time for combustion. All the conditions neces- sary for complete or smokeless combustion may be met by properly constructed furnaces and in- telligent firemen. In recent years a number of American States have authorized some or all cities within their boundaries to prohibit the emission of dense smoke from chimneys and smoke-stacks and to establish special departments to abate the smoke nuisance. In 1903 such departments existed in Chicago, Saint Louis, and Cleveland. In New York the local Board of Healtli has authority in this matter. The smoke nuisance has also been the subject of general legislation in foreign coun- tries, notably in Great Britain. Bibliography. Littlejohn, article "Effects of Smoke and Fog on Health," in the Hanitanj Rec- ord (June 18, 1897: also November 4, 1898); Journal of the Franklin Institute (Philadelphia, 1897-98, and 1898) containing the reports made to the committee appointed to investigate the subject of smoke prevention by various special- ists; '"Coal Combustion and Smoke Prevention." in American Gas-Light Journal, August "29, 1898. SMOKE PIPE. A pipe, usually of thin iron or steel, which serves to conduct the smoke and gases of a steam boiler to the open air. In large vessels there are usually several smoke pipes, which in some instances have a diameter of ninre than 2.5 feet and a height of 125 feet above the furnaces. The area of the cross-section of the pipe depends upon the amount and speed of the gases which are expected to escape through it. The speed of the moving gases (i.e. the draught) is much accelerated by increasing the height and a due consideration of this fact has added con- siderably to the length of smoke pipes in recent years. On modern seagoing vessels they are usually surrounded by tliin sheet-iron casings, leaving air spaces between these and the smoke pipes proper. This plan ])revGnts surrounding objects from being injured by the heat and the casing remains at a temperature sudiciently low to permit of its being kept neatly painted. The various steamship companies in many cases have adopted different colored bands or painting for the smoke pipes of their sliips as distinguishing marks. SMOKY (or Gke.t Smoky) MOUNTAINS. A division of the Appalachians. See Un.k. !M0L .M.VINS. SMOLENSK, smo-lyensk'. A government of Russia, bounded by Tver on the north, Moscow and Kaluga on the east, Orel on the southeast, and Mohilev, Vitebsk, and Pskov on the west (Map: Russia, D 3). Area, about 21.640 square miles. The northern part belongs to the central elevation of European Russia and is generally hilly. In the south and the east the surface is mostly level, and marshy in the northwest. The Government of Smolensk is well watered by the Dnieper, Diina, and several tributaries of the Volga and the Oka. The soil is mostly unfertile and about one-third of the government is still covered with forest. The principal agricultural products are rye, oats, and flax. Stock-raising is in a state of decline. The house industry is only slightly developed. Of late there has been a considerable growth in the manufacturing in- dustries. Oil, textiles, trimmed lumber, and spirits are the chief products. The population, in 1897, was 1..5.51,068, chiefly Great and White Russians. The mediieval Principality of Smo- lensk is mentioned first as a separate State in 1054. It attained great power in the twelfth century, but declined greatly under the sway of the Tatars and was annexed to Lithuania at the beginning of the fifteenth century. The region was permanently reunited with Russia in 1654. SMOLENSK. The capital of the Government of Smolensk, Russia, situated on the Dnieper, 260 miles west-southwest of Moscow (Map: Rus- sia, D 4). The main part of the city on the left bank of the river is surrounded by the rem- nants of the old walls and contains the Uspenski Cathedral, with a venerated picture of the Virgin. There are a seminary for priests, and a historico- philological mviseum. The philanthropic institu- tions are numerous. There are few industries and the export trade is unimportant. Population, in 1897, 46,899. Smolensk is one of the oldest cities of Russia and is mentioned by Nestor as the capital of the Krivitches. It was the capital of the Principality of Smolensk and later obtained Magdeburg rights and other privileges from Lithuania. In 1514 it was taken by the Rus- sians and in 1611 it was recovered by the Poles, after a siege of twenty months. With its final annexation to Russia in 1654 Smolensk was de- prived of its privileges and gradually lost its importance. It plaj'ed a prominent part in the wars of Peter I. with the Swedes and is espe- cially noted as the scene of a fierce engagement between the French and the Russians on August 17, 1812. in which the Russians were defeated and retreated to Moscow. SMOL'LETT, Tobias George (1721-71). A British novelist, descended from an old and re-
