268. Of the other considerable rivers flowing into the Atlantic Ocean are the Elbe (690 miles) and the Weser (380 miles) to the north, and the Meuse (550 miles), Seine (430 miles), Loire (570 miles), and Garonne (350 miles), to the south. Spain is watered by numerous rivers, as the Minho (200 miles), the Douro (160 miles), the Tagus (510 miles), and the Guadiana (450 miles); they are all navigable in the lower parts of their courses. The Guadalquiver (290 miles) is navigable for large vessels up to Seville.

269. The rivers which flow into the Mediterranean have generally short courses, owing to the nearness of the mountains on the north. The Ebro (420 miles) flows from the eastern side of the Spanish table-land. The Rhone (490 miles) rises in the highest region of the Alps, and passing in its course through Lake Geneva, below which it is navigable, falls into the Gulf of Lyons. The Arno (150 miles) and the Tiber (210 miles) both water the western side of the Italian peninsula; the Po (450 miles) and the Adige (250 miles) flow through the plain of Lombardy, and enter the Adriatic Sea near its northern extremity.

270. Of the rivers flowing into the Baltic Sea are the Duna (450 miles), the Niemen (400 miles), the Vistula (630 miles), and the Oder (550 miles). The Duna, the Vistula, and the Oder are navigable for the greater part of their courses. The Neva, which flows into the head of the Gulf of Finland, though only 46 miles in length, is of considerable importance, and has a vast volume of water, since it is the outlet of the great lakes of Ladoga and Onega: it has a mean breadth of 1,500 feet and a depth of 50 feet, but is frozen over for five months of the year.

271. The White Sea and Arctic Ocean receive several important streams, among which are the Dwina (760 miles), the Mezen (480 miles), and the Petchora (500 miles).

274. The Ganges (1,460 miles) and the Indus (1,700 miles), two of the most important rivers of Asia, both water the northern portion of Hindoostan. The Ganges, whose basin extends from east to west to the south of the Himalaya Mountains, flows in an easterly direction into the head of the Bay of Bengal. At its mouth it divides into numerous arms, which inclose a delta of immense extent (page 30): its most western arm, called the Hoogly, upon which Calcutta is built, is the only one that is usually navigated. The Ganges is remarkable for the great extent of its fall: it is ascended by steamers as high as Allahabad, more than 800 miles from its mouth.

275. The Indus rises on the plateau of Tibet, to the northward of the Himalaya Mountains, at an elevation of more than 15,000 feet, and flows into the Arabian Sea. About 470 miles above its mouth the Indus receives on its left bank the river Chenaub, which collects the waters of the five streams of the Jeloam, the Chenaub, the Ravee, the Bayas, and the Sutlej The district watered by these five rivers is called the Punjaub.* All the chief tributaries of the rivers, as well as the main stream, are navigable through nearly their entire length ; steamboats of considerable size can ascend to more than 500 miles distance from the sea, and smaller vessels to 1,000.

276. Of the other principal rivers belonging to the basin of the Indian Ocean are the Saleun and the Irawaddy (1,200 miles), both flowing into the Gulf of Martaban; the Brahmapootra, the Godavery, the Krishna, and the Cauvery, into the Bay of Bengal; the Nerbudda into the Gulf of Cambay; and the united Euphrates (1,600 miles) and Tigris (980 miles) into the Persian Gulf.

LESSON IX.

RIVER SYSTEMS OF THE EASTERN CONTINENT-(CONTINUED). 272. ASIATIC RIVERS.-The rivers of Asia may, like those of Europe, be divided into two principal classes, separated by the mountains and table-lands which extend east and west through the interior. The northern division embraces the rivers which flow into the Arctic Ocean, and those (in the west) which terminate in inland seas or lakes unconnected with the ocean. The other and more numerous class includes the streams which have their origin in the mountains of the interior, and flow either southerly into the Indian Ocean, or eastwardly into the Pacific.

273. The Obi, which flows into the Arctic Ocean, is 2,530 miles in length; its river-basin is 1,250,000 square miles in extent, being probably the largest basin of any river in the

Questions.-268. Other considerable rivers flowing into the Atlantic Ocean? Rivers of Spain? 269. What is said of the rivers flowing into the Mediterranean? The Ebro ? Rhone? Other streams? 270. The principal rivers flowing into the Baltic Sea? Which are navigable? The Neva? 271. Streams flowing into the White Sea and Arctic Ocean? 272. How may the rivers of Asia be divided? The northern division? The other class? 278. The Obi? Other considerable rivers of northern Asia?

RIVER TIGRIS, AT BAGDAD.

277. The seas to the east of Asia receive several large rivers, among which are the Amour (2,300 miles), which flows int the Gulf of Tartary; the Hoang-Ho (2,600 miles), and the Yang-tse-Kiang (3,200 miles), both flowing into the Yellow Sea; and the Cambodia (2,000 miles), into the Gulf of Siam.

Questions.-What further is said of the Obi, Yenesei, and Lena? 274. The Ganges and Indus? Give particulars of the Ganges. 275. The Indus. Its tributaries? How far navigable? 276. Name the principal rivers belonging to the basin of the Indian Ocean. 277. Those flowing into the eastern seas.

Properly, Peenj-ab, or five rivers.

278. The drainage of a large part of the Asiatic continent probably not less than four and a half millions of square milesis unconnected with any of the surrounding oceans, but is received into inland seas or lakes, of which the Caspian and Aral possess the most extended basins. The principal continental rivers of Asia are the Kour (550 miles), the Amoo or Jihon (1,300 miles), and the Sihoon (1,150 miles), flowing into the Sea of Aral. The Tarim or Erghue (900 miles) flows into the Lake of Lop, in the center of the continent. The Helmund (600 miles), which rises in the plateau of Afghanistan, falls into Lake Zurrah; and the Jordan, in Palestine, into the Dead Sea.

279. AFRICAN RIVERS.-The Nile is the most considerable river of Africa: it carries off the waters from the northern and western sides of the plateau and mountains of Abyssinia, and discharges itself into the Mediterranean. The Nile is formed by the junction (in latitude 15° 40′ north) of two streams,-the Bahr-el-Azrek (Blue River), and the Bahr-el-Abiad (or White River): the latter is generally admitted to constitute the main channel of the river. The wonderful secret of the source of the Nile, for centuries a geographical mystery, has lately been unraveled by the intrepid and successful travelers, Speke, Burton, and Grant. It rises in an extensive lake called Victoria Nyanza, lying beneath the equator. A short distance of the course of the river remains unexplored; but its origin is no longer doubtful.

280. Though the Nile has so great a length of course- -probably not much short of 3,500 miles-its basin is of very limited extent. For a distance of 1,400 miles above its mouth it receives no tributary. Through the middle and lower portion of its course, the Nile flows in a narrow valley inclosed on either side by steep rocks; the width of this valley varies from one to two miles in Nubia and Upper Egypt to as many as ten or twelve miles lower down the stream.

281. The Niger (or Quorra) is the largest of the African rivers which flows into the Atlantic Ocean. It rises in the mountains of Soudan, where the main tributary is known as the Joliba, pursues a northeasterly course to the neighborhood of Timbuctoo, thence a southeasterly course, passing through a wide opening of the Kong Mountains, and enters the eastern extremity of the Gulf of Guinea by several mouths. The length of the Niger is perhaps about 2,300 miles; above the place of its passage through the Kong Mountains it receives the waters of the Chadda, a broad and deep tributary. The Niger has been ascended by a steamboat to more than two hundred miles above the junction of the Chadda, but the extreme unhealthiness of the climate, in the district through which its lower course lies, has contributed to the failure of many attempts made to explore this part of Africa, and to establish commercial relations with the inhabitants.

282. Besides the Niger, the principal rivers upon the west coasts of Africa are the Senegal, the Gambia, the Rio Grande, the Rokelle, the Volta, the Zaire or Congo, the Coanza, and the

Questions.—278. Extent of the surface drained into the inland seas? Principal continental rivers of Asia? Into what seas or lakes do they respectively flow? 279. What is said of the Nile? How formed? Source of the Nile? In what does it rise? Exploration of the river? 280. Length? Basin? Width of the valley in different parts? 281. The Niger? Its source, direction, and termination? Length ? How far ascended by a steamboat? The climate of the district in which its lower course lies? 282. Other principal rivers upon the west coasts of Africa?

LESSON X.

LAKES.

283. FRESH-WATER lakes occur in the greatest numbers, and upon the largest scale, in the northern regions of the globe. Nearly all the lakes of any considerable extent in North America are situated north of the 40th parallel, while in Europe and Asia, the regions peculiarly characterized by fresh-water collections are, for the most part, north of the 50th parallel. Saltwater lakes have a more southerly distribution, and are very abundant in eastern Europe, and central and southern Asia.

284. Lakes may be divided into four classes, according to certain physical peculiarities. The first class includes those which have no outlet, and do not receive any running water. Lake Albano, near Rome, is an example. Many of these lakes are situated in elevated districts, and are generally small; it has been supposed that they are the craters of extinct volcanoes, and are supplied by springs.

285. The second class comprises those which receive water, but have no apparent outlets. The Caspian Sea and Lake Aral belong to this division. The Caspian is about 600 miles long; its extreme breadth is 300 miles, though its average breadth is not more than 100 miles. This most remarkable lake receives the waters of the Volga, a river which has a course of 2,200 miles, and brings down more than 518,000,000 cubic feet of water every hour. The Ural and many other streams of considerable magnitude are also received by the Caspian; but its level is not changed, though it has no perceptible outlet by which to discharge the water it receives.

286. Lake Aral presents the same phenomenon, and, though not to be compared in extent to the Caspian, receives two large rivers, the Sihoon and Amoo or Jihon. The difficulty in explaining the nature of these lakes is to account for the constancy of their level, which might be expected to rise considerably, as they are daily receiving so large a body of water. The opinion was entertained that they are connected by some internal channel with the sea, and it was supported by the fact that the water of both the Caspian and Lake Aral is salt, and

Questions.-The Senegal and the Gambia? The Gariep? The principal river upon the eastern side? Other rivers? 283. Where are fresh-water lakes most abundant? In North America? In Europe and Asia? Salt-water lakes? 284. Into how many classes may lakes be divided? First class? Example. Situation of these lakes, etc.? 285. Seeond class? Examples. The Caspian? What waters are tributary to it? 286. Lake Aral? Opinion formerly entertained? How supported? How is this hypothesis disproved? How may the constant level be accounted for? What other lakes belong to this class?

contains marine productions; but it has been ascertained that the Caspian is not less than 84 feet below the level of the Black Sea, thus completely disproving the hypothesis that they have a connection. It is thought that the phenomena referred to may be accounted for by evaporation and filtration. Besides the Caspian Sea and Lake Aral, there are numerous other bodies of water of this class, the receptacles of the continental rivers. (See table of Continental Rivers, page 31.)

287. A third class comprehends all those lakes which receive no streams, but give birth to some. Many of these lakes Occupy very elevated situations, and are the sources of some of the largest rivers. They are no doubt supplied by springs, the waters of which rise in their reservoirs until its level is sufficiently high to admit a discharge. The lake in Monte Rotondo, in Corsica, is one of this class, and is situated 9,000 feet above the level of the sea.

288. The fourth class includes all those lakes which both receive and discharge water, being by far the most numerous division. They commonly receive the waters of many rivers, and have but one outlet. The origin of such rivers is easily explained. Should a hollow present itself in the course of a river, it evident that it must be filled to the level of some part of its banks before the river can proceed, and this would produce a lake. But it may happen that there is a general declivity from various parts of a district toward some central valley, and then the waters of a number of rivers may be brought into it, while at the same time the continuation gives but one course by which the waters can be discharged. A description of some of the largest lakes of this class will bet given in the next lesson.

289. Most lakes occur at varying elevations above the level of the sea, while some are much below it. The highest known lake in the world is Sir-i-kol, in Asia. It is the source of the

LAKE TITICACA.

Amoo River, and is 15,630 feet above the level of the ocean. Lake Titicaca, in Bolivia, has an elevation of 12,785 feet; Tzana or Dembea, in Abyssinia, 6,076 feet; Lake Baikal, in Asia, 1,793 feet; Constance, 1,299 feet; Geneva, 1,229 feet; Great Salt Lake, in Utah Territory, 4,200 feet; Superior, 623 feet; Huron and Michigan, 591 feet; Erie, 565 feet; Ontario,

Questions.-287. Third class? What is said of many of the lakes of this class? How supplied? Monte Rotondo? 288. Fourth class? How is the origin of such lakes explained? 289. Varying elevations and depressions of lakes? Highest known lake, its elevation, etc.? Give the elevations of the other lakes mentioned. State the depressions of the Caspian, Lake of Tiberias, and the Dead Sea. 290. Which are the largest lakes in North America, and how drained?

234 feet. The Caspian Sea, Lake of Tiberias, and the Dead Sea are each below the sea-level,-the first 84 feet. the second 600 feet, and the third 1,317 feet.*

LESSON XI.

LAKES (CONTINUED).

290. NORTH AMERICAN LAKES.-The largest lakes in North America are Superior, Huron, Michigan, Erie, and Ontario, which are connected with the sea by the channel of the river St. Lawrence; Winnipeg, which is drained by the river Nelson into the Hudson Bay, and the Athabasca, Great Slave, and Great Bear, which empty their waters into streams tributary to the Arctic Ocean.

291. Lake Superior is the largest fresh-water formation on the globe, computed to have an area of 40,000 square miles; length 420 miles; extreme breadth, 165; height above the level of the Atlantic, 623 feet; greatest depth, 1,200 feet. There is reason to believe, from the appearance of the shores, that the waters of this, as well as the other Canadian lakes, formerly occupied a much higher level than they reach at presThe amount of water carried off by its outlet, the river of St. Mary, is much less than that received by its tributaries, from which circumstance it is inferred that the evaporation from its surface must be very great.

ent.

292. Lake Huron, remarkable for its brilliant transparency, has an area of 25,000 square miles. It is about 240 miles in length, from 180 to 220 in breadth, and is 591 feet above the level of the sea. The outline of this lake is very irregular, and its shores are described as consisting of clay cliffs, rolled stones,

abrupt rocks, and wooded steeps. The greatest depth of Lake Huron is found to be nowhere more than 450 feet. Lake Michigan, which lies wholly within the United States, is connected with Lake Huron by means of the navigable channel Mackinaw. It is about 300 miles long, and has an area of about 25,000 square miles.

293. Lake Eric has an area of about 11,000 square miles; its surface is 565 feet above the sea. This lake is said to be the only one in the whole Canadian chain in which there is any perceptible current, a circumstance which is supposed to be attributable to its comparative shallowness, its average depth being not more than 60 or 80 feet. The current of Lake Erie, which runs always in one direction, combined with the great prevalence of westerly winds, and the occurrence of sunken reefs and

209. Givo Questions.-291. Give particulars of Lake Superior. Change of level? particulars of Lake Huron. Lake Michigan. 293. Lake Eric. What is said of its cur rent? Its navigability?

According to the measurement made by Lieutenant Lynch, in 1948, the exact depression of the Dead Sea below the Mediterranean was found to be 1,816.7 feet.

rocky banks, form serious obstacles to the safe and easy navigation of this lake. The shallowness of the water of Lake Erie likewise causes it to be more readily and more permanently affected by frost, so that its navigation is usually obstructed by ice for some weeks every winter, while that of the other lakes continues open and unimpeded.

294. Lake Ontario has a computed area of 10,000 square miles, 234 feet above the sea-level, and 331 feet below the level of Lake Erie. Its depth is said to be very great, and it is navigable throughout its whole extent for the largest ships. Its outlet is a spacious channel studded with islands, collectively denominated the Thousand Isles, but no less than 1,692 have been actually counted.

295. Lake Champlain (about 500 square miles) belongs to the same basin as the great lakes above described, and is connected with the St. Lawrence by the river Richelieu. Lake George, noted for its picturesque scenery, and for the transparency of its waters, is situated west of the southern extremity

coast of the Pacific is only eleven miles; it is drained by the San Juan, which flows into the Caribbean Sea.

298. SOUTH AMERICAN LAKES.-South America has few lakes of any great extent. The largest is Lake Titicaca (about 3,800 square miles), situated on a plateau of that name, at an elevation of 12,785 feet, and surrounded by some of the highest summits of the Andes. The water of Lake Titicaca is fresh; a river called the Desaguadero, which leaves its southern extremity, flows into the smaller lake (or marsh) of Aullagas, or Uros, which lies at 490 feet lower level, and the water of which is salt.

299. Lake Maracaybo (5,000 square miles), near the coast of the Caribbean Sea, is connected by a narrow strait with the Gulf of Maracaybo, and has brackish water. The Lake dos Patos and Lake Mirim are on the southeast coast of Brazil.

LESSON XII.

LAKES (CONTINUED).

300. EUROPEAN LAKES.-There are two principal lake-regions in Europe, one lying around the Baltic, and situated within its basin; and the other embracing the Alpine system of mountains. The lakes situated in the former of these regions possess, in general, greater magnitude, while the latter are distinguished by their great elevation above the sea, and by the grandeur of the scenery among which they lie.

301. The following tables give the dimensions of the prin cipal European lakes, together with their elevation and greatest depth, where these particulars have been ascertained.

LAKES SITUATED ROUND THE BALTIC.

LAKE GEORGE.

HITNEY-LOCELYN-ANNIN

of Lake Champlain, with which it is connected by a short stream. It is about 30 miles long, and from one to two miles broad.

296. The Great Salt Lake (about 2,600 square miles), situated in the great basin between the Rocky Mountains and the Sierra Nevada (111), is about 70 miles in length, from 30 to 35 miles in breadth, and is about 4,200 feet above the level of the sea. Its waters are saturated with common salt, and when the lake is low, considerable quantities of this substance are precipitated to the bottom of the lake, or, rather, are there crystallized. No living animal can exist in this lake. It receives the waters of the Bear, Weber, and other rivers, but, like other lakes in this region, has no connection with the ocean.

297. Upon the Mexican plateau is the large lake of Chapala (about 650 square miles), which is discharged into the Pacific by the river Santiago. Lake Nicaragua (about 3,500 square miles), in Central America, lies at an elevation of about 128 feet above the sea. The distance between its western shore and the

Questions.-294. Give particulars of Lake Ontario. The Thousand Isles. 295. Lake Champlain. Lake George. 296. Great Salt Lake. What are its waters? 297. Give particu lars of Lake Chapala. Lake Nicaragua. 298. What is said of South America? Lake TitiLaca? 299. Lake Maracaybo? Other lakes? 800. How many lake-regions are there in Europe, and where are they respectively situated? How are the lakes of each division characterized? 801. What is the area of Lake Ladoga? Of Onega?

IN SWEDEN..... Wener

Wetter.. Maëlar

302. Lakes are very numerous in Scotland, especially in the middle and northern parts. They are mostly long and narrow bodies of water, occupying the deep hollows within the elevated mountain valleys. The largest lake in Scotland, and also in Great Britain, is Loch Lomond (45 square miles), which is 24 miles in length, and 7 miles in its greatest breadth.

303. Of the lakes in Ireland the largest is Lough Neagh (150 square miles), situated in the north of Ireland, and the Lakes

from this, at a lower elevation, are Lake Little Luta Nzige (unexplored), and Lake Tanganyika or Ujiji. Among other noted African lakes are Tzana or Dembea, in Abyssinia, and Nyanja or Nyassi, and Shirva, in or near the borders of Mozambique.

LAKE KILLARNEY.

of Killarney (three in number), noted for their beautiful scenery, in the south.

304. ASIATIC LAKES.-The largest fresh-water lake in Asia is Lake Baikal, situated among the northern offsets of the Altai mountain-system: it has an area of about 15,000 square miles, and lies at an elevation of 1,793 feet above the level of the sea. Its water is fresh, and abounds in fish. It is annually frozen over for a period of five or six months, and may be traversed on sledges.

305. Among the smaller lakes of Asia are Balkash, Upsa-nor, Zaizang, Issi Kol, Bosteng, Lop, Koko-nor, Bouka-nor, and Tengri-nor-all on or adjacent to the high plateaus in the interior of the continent; Tung-ting and Poyang, in China; Zurrah and Bakhtegan (both salt), on the plateau of Afghanistan and Persia; Ooroomiah, Van, and Goukcha (the two former of which are salt), on the Armenian table-land; the salt lake of Koch-hissar, in Asia Minor; with Lake Tiberias and the Dead Sea in Palestine.

306. AFRICAN LAKES.-The largest body of inland water known in Africa, until recently, was Lake Tsad. It lies in the central part of the continent, and is several thousand square miles in area; but its waters are very shallow. It is not known to have an outlet, but is fresh and clear, and probably has a channel of discharge like other fresh-water lakes.

307. Recent explorations in the southeast of Africa have made known the existence of several large lakes, the most extensive of which is Lake Victoria Nyanza or Ukerewe, the long-sought source of the Nile. Its area is not yet determined, but is believed to considerably exceed that of Lake Tsad. Its height is 3,553 feet above the level of the sea. Not far

ATLANTIC OCEAN......

PACIFIC OCEAN......

INDIAN OCEAN..

ANTARCTIC OCEAN..

I.

Extends from the northern shores of America, Europe, Asia, and the arctic circle around the north pole......

II.

Bounded on the west by America; east by Europe and Africa; north by the arctic, and south by the antarctic circle-divided by the equator into the North and South Atlantic......

III.

Inclosed between America on the east; Asia, the Sunda Isles, and Australia on the west; and the arctic circle on the north; the antarctic on the south-divided by the equator into the North and South Pacific......

IV.

Bounded by Africa on the west; the Sunda Isles and Australia on the east; southern Asia on the north; and the antarctic circle on the south....

V.

Extends from the antarctic

Branches.

Baffin Bay. White Sea. Gulf of Kara. Gulf of Obi.

Baltic with its gulfs.
North Sea.
Mediterranean.
Black Sea.
Hudson Bay.
Gulf of Mexico.
Caribbean Sea.

Sea of China.
Yellow Sea.

Sea of Japan.
Sea of Okhotsk.

Sea of Kamtchatka
Behring Strait.

Gulf of California. J Bay of Panama.

circle around the south pole. }

Red Sea. Arabian Sea. Persian Gulf. Bengal Sea.

309. The Arctic Ocean has been but partially explored. Various efforts have been made to reach its higher latitudes, but, up to this time, they have proved unsuccessful, in consequence of the impenetrable fields of ice which are met with, and the impossibility of remaining in those regions with safety for a great length of time. During the winter months the waters of the Arctic Ocean are covered with ice, which in summer is broken up and drifted into lower latitudes, where it is dissolved.

Questions.-808. Under what general name is the vast body of water which surrounds the land comprehended? How is it divided? Describe the situation, and mention the principal bran hes of the Arctic Ocean, Atlantic, Pacific, Indian, Antarctic. 309. What is said of the Arctic Ocean? Why have the efforts made to reach its higher latitudes been unsuccessful?