Page:EB1911 - Volume 22.djvu/223

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209
POTOMAC—POTOSI

Polish Succession (Pol.) (Amsterdam, 1789); Protest against the Succession to the Throne (Pol.) (ibid. 1790); and other political works.

See Friedrich Schulz, Poland in the year 1793 (Pol.) (Warsaw, X899); Josef Zajaczek, History of the Revolution of 1794 (Pol.) (Lemberg, 1881).  (R. N. B.) 


POTOMAC, a river in the east central part of the United States, having its source in the Alleghany Mountains and flowing S.E. into Chesapeake Bay. It is formed by the union of its north and south branches, about 15 m. S.E. of Cumberland, Maryland. The main stream has a length of about 450 m. and is navigable for large vessels for 113 m. above its mouth. The north branch, about 110 m. long, rises in the north-eastern part of West Virginia, pursues a north-easterly course, and forms part of the boundary between Maryland and West Virginia. The south branch has its sources in Highland county, Va., and in Pendleton county, W.Va., and flows north-east for about 140 m. until it joins the north branch. From the junction of these two streams until it reaches Harper's Ferry the Potomac river separates Maryland from West Virginia. At Harper's Ferry it receives the waters of the Shenandoah river and cuts through the Blue Ridge Mountains in a gorge noted for its scenic beauty. From this point to its mouth it forms the boundary between Virginia and Maryland. The stream crosses the Blue Ridge Mountains at an elevation of about 245 ft., and at Georgetown (Washington), 62 m. distant, it meets tidewater. Of this descent about 90 ft. occurs about 15 m. above Washington, at the Great Falls, a series of rapids about a mile long and including a cataract about 35 ft. high. Three and a half miles above Washington are the Little Falls, which mark the head of navigation. Large vessels, however, are prevented by a bridge from proceeding above Georgetown. At Washington there are two channels, with respective depths at mean low water of 18 and 21 ft. Large sums have been spent since 1870 on improving these channels. A few miles below the city the river broadens into a deep tidal estuary from 2½ to 7 m. wide; and channels 24 ft. deep and 200 ft. wide through all the shoals were secured by the project of 1899. The Anacostia river, or “ East Branch,” which flows into the Potomac just south of Washington, is navigable for large vessels for about 2 m. and for small scows and lighters as far as Bladensburg, Md., 8¾ m. above its mouth; its natural channel was narrow and tortuous and about 18 ft. deep; in 1909 improvements (begun in 1902) had procured a channel 20 ft. deep at mean low water and 380 ft. wide. The Chesapeake & Ohio Canal, from Georgetown to Cumberland, Md., follows the Potomac closely on the Maryland side. The shipments over the Potomac above Washington in 1907 were valued at $7,596,494, and those below Washington at $21,093,800, the principal commodities being sand and gravel, ice, oils, naval ordnance and supplies, and building and paving materials. The shipments on the Anacostia river were of much the same character, and in 1907 were valued at $4,312,687.


POTOROO, or Rat Kangaroo, any member of the diprotodont marsupial sub-family Potoroinae (see Marsupalia). None of them exceed a common rabbit in size. They inhabit Australia and Tasmania, are nocturnal, and feed on the leaves of grasses and other plants, as well as roots and bulbs, which they dig up with their forepaws; in this wav some of them do considerable damage to cultivated crops. About ten species are known, presenting a considerable range of diversity in minor characters. The members of the type genus (Potorous) run, rather than leap, and do not use the hind feet for kicking. In the genus Bettongia the tail is prehensile, and with it they collect grass and twigs for making nests in their burrows.


POTOSÍ, a department of Bolivia occupying the south-western angle of that republic, bounded N. by Oruro, Cochabamba and Chuquisaca, E. by the two last departments and Tarija, S. by Argentina and W. by Chile and Oruro. Pop. (1900), 325,615, the larger part Indians; area, 48,801 sq. m. The eastern part of the department is traversed north to south by the eastern branch of the Andes, locally known as the Cordillera de los Frailes and the Sierras de Chichas. Spurs and broken ranges project eastward from these, between which are the head streams of the Pilcomayo and Guapay, the first flowing south-east to the La Plata, and the second north-east to the Madeira and Amazon. The Pilcomayo itself rises in the department of Oruro, but several of its larger tributaries belong to Potosi-the San juan, Cotagaita and Tumusla in the south, and Cachimayo in the north. The western part of the department belongs to the great Bolivian altaplanicie, or southern extension of the Titicaca basin. It is a barren, saline waste, almost uninhabitable. In the north, bordering on the transverse ridge of which the Cerro de Tahua (17,454 it.) forms a part, is the depression known as the Pampa de Empeza, 12,080 ft. above sea-level, which is largely a region of morasses and saline plains. On and near the southern frontier is another transverse ridge, in part formed by the Sierra de Lipez, and in part by apparently detached groups of high peaks; it is a waterless desert like the Puna de Atacama. Potosi is essentially a mining department, though agriculture and grazing occupy some attention in the eastern valleys. The western plateau is rich in minerals, especially silver and copper. The Huanchaca group of mines, situated on the slopes of the eastern Cordillera, Overlooking the Pampa de Empeza, has the largest output of silver in Bolivia. The Pulacayo mine, belonging to this group, 15,153 ft. above sea-level, ranks next to the Broken Hill mine of Australia in production. Between 1873 and 1901 it yielded 4520 tons of silver, of an estimated value of £23,200,000. Farther south are the Portugalete mines, once very productive, and near the Argentine border are the Lipez mines. East of the Cordilleras are the famous “silver mountain " of Potosi, once the richest silver mine in the world; the snow-capped peak of Chorolque (18,452 ft.), which is claimed to have the highest mine in the world; Porco, a few miles south-west of Potosi; Guadalupe, Colquechaca and Aullagas. Besides silver, the Chorolque mines also yield tin, copper, bismuth, lead and Wolfram. In 1907 the national government undertook railways from Potosi to Oruro, 205 m., and from Potosi to Tupiza, 155 m., to connect with the Central Northern line of Argentina, which was opened to Quiaca on the frontier on the 25th of May 1908. In western Potosi the department is traversed by the Antofagasta & Oruro railway (0~75 metre gauge). Besides Potosi, the capital of the department, the principal towns are Huanchaca (pop. about 10,000 in 1904), the seat of famous silver mines, 13,458 ft. elevation, and overlooking the Pampa de Empeza; Uyuni, 9 m. from Huanchaca, 12,100 ft. above sea-level, a small town but an important railway junction and commercial centre on the waterless plain, the shipping point and 'supply station for an extensive mining region; and Tupiza (pop. about 5000 in 1906), a prettily situated town near the Argentine frontier, on a small branch of the San juan river, 9800 ft. above sea-level.


POTOSÍ, a city of Bolivia, capital of the department of Potosi, 47 m. (direct) S.W. of Sucré, or 88 m. by the post-road. Pop. (1906, estimate), 23,450. Potosi stands on a barren terrace on the northern slope of the Cerro Gordo de Potosi, 12,992 ft. above sea-level, and is one of the highest towns in the world. The famous cewo from which its name is taken rises above the town to a height of 15,381 ft., a barren, white-capped cone honeycombed with mining shafts. The town is regularly laid out with streets crossing each other at right angles. The smoke begrimed buildings, many of which are unoccupied and in ruins, are commonly of adobe. A large plaza forms the conventional centre, around which are grouped various religious edifices, the government house, town hall, national college, the old “ royal mint ” dating from 1585, and the treasury. The city has a massive, plain cathedral, which in part dates from early colonial times, and in part from the closing years of Spanish rule. The water supply is derived from a costly system, of reservoirs and aqueducts constructed by the Spanish government during the years of the city's greatest prosperity. There are 27 of these artificial lakes, and the aqueducts originally numbered 32, some of which are no longer serviceable. Rough mountain roads and pack animals are the only means of transportation to and from Potosi, but a railway from Oruro to Tupiza via Potosi, forming part of the projected Pan-American route, was contracted for in 1908. In 1611 the population of Potosi was reported to be 160,000, which probably included the whole mining district. A part of the diminution since then is explained by the fact that the great majority of the mines on the cerro have been abandoned.