between them, so that they become engaged columns, as in the great temple at Agrigentum. In Roman temples, in order to increase the size of the cella, the columns on either side and at the rear became engaged columns, the portico only having isolated columns. (See Temple.)
PSEUDOPOD, Pseudopod, the name given to an extension
of the naked protoplasm of certain Protozoa, notably the
Sarcodina (q.v.), for crawling or creeping or for the pretension of food, but not for active swimming (see also Amoeba).
PSILOMELANE, a mineral consisting of hydrous manganese
oxide with variable amounts of barium, potassium, &c. It is
sometimes considered to be a hydrous manganese manganate, but
of doubtful composition. The amount of manganese present
corresponds to 70–80% of manganous oxide with 10–15% of
“available” oxygen. The mineral is amorphous and occurs as
botryoidal and stalactitic masses with a smooth shining surface
and submetallic lustre. The name has reference to this characteristic
appearance, being from the Greek ψιλός (naked,
smooth) and μέλας (black); a Latinized form is calvonigrite,
and a German name with the same meaning is Schwarzer Glaskopf.
Psilomelane is readily distinguished from other hydrous manganese
oxides (manganite and wad) by its greater hardness (H. = 512);
the sp. gr. varies from 3·7 to 4·7. The streak is brownish-black
and the fracture smooth. Owing to its amorphous nature,
the mineral often contains admixed impurities, such as iron
hydrates. It is soluble in hydrochloric acid with evolution of
chlorine. It is a common and important ore of manganese,
occurring under the same conditions and having the same commercial
applications as pyrolusite (q.v.). It is found at many
localities; amongst those which have yielded typical botryoidal
specimens may be mentioned the Restormel iron mine at
Lostwithiel in Cornwall, Brendon Hill in Somerset, Hoy in the
Orkneys, Sayn near Coblenz, and Crimora in Augusta county,
Virginia. With pyrolusite it is extensively mined in Vermont,
Virginia, Arkansas and Nova Scotia.
PSKOV, a government of the lake-region of north-west Russia, which extends from Lake Peipus to the source of the west Dvina, having the governments of St Petersburg and Novgorod on the N., Tver and Smolensk on the E., Vitebsk on the S. and Livonia on the W. It has an area of 17,064 sq. m. In the south-east it
extends partly over the Alaun or Vorobiovy heights, which stretch
west into Vitebsk and send to the north a series of irregular
ranges which occupy the north-western parts of Pskov. A
depression 120 m. long and 35 m. broad, drained by the Lovat
and the Polista, occupies the interval between these two hilly
tracts; it is covered with forests and marshes, the only tracts
suitable for human occupation being narrow strips of land
along the banks of the rivers, or between the marshes, and no
communication is possible except along the watercourses.
With the exception of the south-eastern corner, where Carbonifer ous rocks crop out, nearly the whole of the government consists of Devonian strata of great thickness, with deposits of gypsum and white sandstone, the latter extensively quarried for building purposes. The botton; moraine of the Scandinavian and Finnish ice-sheet formerly extended over the whole of this region, and has left behind it numerous ridges (kames or eskers), the upper parts consisting of Glacial sands and post-Glacial clays, sands and peat-bogs. The soil is thus not only infertile, but also badly drained, and only those parts of the territory which are covered with thicker strata of post-Glacial deposits are suitable for agriculture.
The rivers are numerous and belong to three separate basinsto Lakes Peipus and Pskov the rivers in the north-west, to Lake Ilmen those in the middle, and to that of the Dvina the rivers in the south-east. A great number of small streams pour into Lake Pskov, the chief being the Velikaya. The Lovat and the Shelon, belonging to the basin of Lake Ilmen, are both navigable; while the west Dvina flows for 100 m. on the south border of the government or within it, and is used only for floating timber. There are no fewer than 850 lakes in Pskov, with a total area of 391 sq. m. The largest is Lake Pskov, which is 50 m. long and 13 broad, covers 300 sq. m. and has a depth of 3 to 18 ft.; it is connected by a channel, 40 m. long and 3 to 10 wide, with Lake Peipus. The marshes on the banks of the Polista are nearly 1250 sq., m. in extent. Forests occupy nearly one-third (32%) of the entire area, and in some districts (Kholm, Toropets, Porkhov) as much as two-thirds of the surface. Large pine forests are met with in the north; in other parts the birch and the aspen prevail; but almost one-quarter of the forest area is overgrown with brushwood.
The climate is very moist and changeable. The average temperature is 41° F. (17·1° in January and 64·8° in July).
The population of the government numbered 1,135,639 in 1897, when there were 584,931 women, and the urban population only 72,623. The estimated population in 1906 was 1,275,300 With the exception of 25,460 Esthonians (1897), the inhabitants are almost entirely Great Russians. They belong mainly to the Orthodox Greek Church, but the official number of Nonconformists, 32,066, is far below the mark. There are also about 12,000 Lutherans and 4000 Roman Catholics. The government is divided into eight districts, the chief towns of which, with their populations in 1897, are Pskov (q.v.), Kholm (5899), Novorzhev (2973), Opochka (5658), Ostrov (6252), Porkhov (5573), Toropets (7489) and Velikiye Luki (8481). Between 1875 and 1896 the peasantry increased their landed possessions by 91%, and the merchants bought considerable areas from the nobles, who altogether sold 43% of their estates. Although the soil is far from fertile, no less than 3070 of the total area is under crops and 12% under meadows. The crops principally cultivated are rye, oats, barley, pease, potatoes, flax (for which the government is famous) and hemp. Grain has to be imported, but oats are exported. Owing to the efforts of the zemstvos, there has been a notable improvement in agriculture, especially in dairy farming. Fishing in Lake Pskov and the smaller lakes is a source of income. The manufacture of wooden wares for local needs, ship-building, the timber trade, and the weaving of linen and woollens for local requirements are additional sources of income. Flax, flour, tobacco factories, saw-mills, distilleries and breweries are the principal industrial establishments. The population engage also in the preparation of lime, in stone-quarrying, and in the transport of merchandise. (P. A. K.; J. T. Be.)
PSKOV, in German, Pleskau, a town of Russia, capital of the government of the same name and an archiepiscopal see of the Orthodox Greek Church, situated on both banks of the Velikaya River, 9 m. S.E. from Lake Pskov and 170 m. by rail S.W. of St Petersburg. Pop. (1897), 30,424. The chief part of the town, with its kremlin on a hill, occupies the right bank of the river, to which the ruins of its old walls (built in 1266) descend; the Zapskovye stretches along the same bank of the Velikaya below its confluence with the Pskova; and the Zavelichye occupies the left bank of the Velikaya—all three keeping their old historical names. The cathedral in the kremlin has been four times rebuilt since the 12th century, the present edifice dating from 1691–1699, and contains some very old shrines, as also the graves of the bishops of Pskov and of several Pskov princes, including those of Dovmont (d. 1299), and Vsevolod (d. 1138). The church of Dmitriy Solunskiy dates originally from the 12th century; there are others belonging to the 14th and 15th. The Spaso-Mirozhskiy monastery, founded in 1156, and restored in 1890–1903, has many remarkable antiquities. The ruins of numerous rich and populous monasteries in or near the town attest its former wealth and greatness. The present town is ill-built, chiefly of wood, and shows traces of decay. It has a cadets' school, a normal school for teachers, and a few lower technical schools, an archaeological museum (1903) and some scientific societies. The private collections (coins, antiquities, art works, &c.) of Messrs Pushkin and Sudhov are two of the most remarkable in Russia. The manufactures are unimportant. Since the completion of the St Petersburg and Warsaw railway the trade of Pskov has increased. Pskov has regular steam communication with Dorpat.
History.—Pskov, formerly the sister republic of Novgorod, and one of the oldest cities of Russia, maintained its independence and its free institutions until the 16th century, being thus
