Page:The American Cyclopædia (1879) Volume VI.djvu/804

 784 EUROPE Poland, and the N. E. part of Prussia ; its great- est elevation, in the plateau of Valdai, is only 1,150 ft. The Ural range, which forms the northern portion of the E. boundary line of Europe, extends from N. to S. through 18 de- grees of latitude, with a general elevation of about 2,000 ft., several summits rising to a height of more than 5,000 ft. Toward the south it diverges into smaller ridges that ex- tend to the Caspian sea, the sea of Aral, and the steppes of the Kirghiz. A volcanic belt extends through the southernmost portion of Europe from central Asia and Asia Minor through the archipelago, Greece, Naples, Si- cily, Spain, and Portugal, to the Azores. Along this line destructive earthquakes are of frequent occurrence. Besides many extinct craters, there are two active volcanoes, Etna in Sicily and Vesuvius near Naples. In the north, Iceland constitutes a distinct volcanic region. Its principal volcano is Mt. Hecla, some irruptions of which have lasted for six years. The S. "W. portion of the island con- tains the famous geysers, or intermittent springs of steam and boiling water. There are two other volcanoes, one on the island of Jan May en, between Iceland and Spitzbergen, the other on the northern island of Nova Zembla. The river systems of Europe are less exten- sive than those of either Asia or America. The principal watershed, running S. W. and N. E., from the strait of Gibraltar to the sea of Kara, divides the continent into a S. E. and a N. W. slope, the former containing about four sevenths and the latter three sevenths of the total area. On the S. E. slope the basin of the Caspian sea comprises over 500,000 sq. m. ; that of the Black sea and the sea of Azov about 950,000 sq. m. ; and the basin of the Mediterranean sea, 575,000 sq. m. On the N. W. slope the Atlantic basin and the basin of the Baltic com- prise about 450,000 sq. m. each, the basin of the North sea 400,000, and that of the Arctic ocean nearly 200,000. The following are some of the more important rivers flowing into the dif- ferent seas : 1, Caspian sea : Ural and Volga ; 2, sea of Azov: Don; 3, Black sea: Dnieper, Dniester, Danube ; 4, Mediterranean : Maritza, Isonzo, Adige, Po, Tiber, Arno, Var, Rh6ne, Ebro; 5, Atlantic: Minho, Douro, Tagus, Guadiana, Guadalquivir ; 6, bay of Biscay : Garonne, Loire ; 7, British channel : Seine, Soinme; 8, North sea: Scheldt, Rhine, Ems, Weser, Elbe, Eider; 9, Cattegat: Glommen; 10, Baltic sea: Ulea, Neva, Diina, Niemen, Vistula, Oder, Dal Elf, Angermann Elf, Umea Elf, Pitea Elf, Lulea Elf, Tornea Elf; 11, Arc- tic ocean : Onega, Dwina, Mezen, Petchora. Besides these, there are the rivers of the Brit- ish islands, the chief of which are the Thames, Severn, Humber, and Mersey, in England ; the Tweed, Clyde, and Forth, in Scotland; the Shannon, Blackwater, Liffey, and Boyne, in Ireland. The largest river of Europe is the Volga, with a course of 2,300 m. and a basin of 500,000 sq. m. ; next comes the Danube, with a length of 1,820 m. and a basin of 300,000 sq. m. Artificial watercourses con- nect the Caspian sea, the Baltic, and the Arctic ocean, by the Volga, Neva, Dtina, and Dwina rivers; the Black and the North sea by the Danube and Rhine ; the Mediterranean and the Atlantic ocean, the British channel and the North sea, by numerous canals between the Rh6ne, Garonne, Loire, Seine, Scheldt, and Rhine. The middle course of most of the large rivers is well adapted to navigation by steam and other vessels, but their usefulness for the purposes of commerce is restricted by obstructions at their mouths. Such is espe- cially the case with the Volga, Don, Danube, and Rhine. The lakes of Europe are small, and scarcely any of them are important to com- merce. The following are among the largest: Ladoga (between 6,000 and 7,000 sq. m.), One- ga, Saima, and Enare, in Russia ; Wener (about 2,000), Wetter, and Mselar, in Sweden; Lake Balaton (450), in Hungary ; the lakes of Geneva and Constance in Switzerland ; and Garda and Lago Maggiore, in Italy. Four fifths of the lakes in Europe are situated in the re- gion around the Baltic sea. (The geology of Europe is treated under the special heads of the different countries and mountain ranges.) The whole of Europe, with the exception of a small northernmost portion of the Scandina- vian peninsula and Russia, being situated with- in the temperate zone, enjoys an equable and temperate climate. The disadvantages arising from the proximity of the Arctic ocean and the climatic influences of northern Asia are more than overborne by many advantages which no other division of the globe enjoys in an equal degree. The prevailing winds are western, and hence before reaching Europe have been in contact with an expanse of water, the surface of which has, even in January and in lat. 45-50 N., rarely a lower temperature than 50 F. In the second place, Europe is in- fluenced by a broad tropical zone, including Af- rica and Arabia, whose dry soil serves to warm the air carried to Europe by southern winds. On the other hand, the influence of the Arctic ocean upon the climate of the continent is neutralized by the Gulf stream. The combina- tion of all these advantages explains the fact that the mean temperature of Europe is higher than that of any other division of the globe in corresponding latitudes, the isothermal lines of Asia and America bending in Europe to the northward by some 10 degrees of latitude. Thus in lat. 36 N. the mean temperature of the year is 66 F., and in lat. 71 N. (Cape North) it is 32 F., not lower than in lat. 56 N. on the E. coast of Asia and America. Owing to the causes before mentioned, the mean tem- perature of Europe is higher and the extremes are less in the same latitudes in the western than in the eastern part. The isothermal line of 50 F. (mean annual temperature) runs from London to Cracow and Odessa, that is to say, from lat. 51 30' to 46 22' N., thus declining