the sea. The belt enclosed between the two first mentioned chains, (¶ 632) contains many fertile tracts, occupied by Dutch farmers. The second terrace contains a large portion of arid soil, and is called the Karoo. The third elevation is a vast plain, about 300 miles long, and 100 broad, called the Great Karoo. It is a complete scene of desolation, and it does not contain a single fixed habitation.

An extensive plateau, or table-land, has recently been discovered in South Africa, north of the Tropic of Capricorn.

INLAND NAVIGATION.

640. Vast regions in Africa, like others in Asia, are so destitute of rivers, that their commerce is carried on entirely by means of the camel, termed "the ship of the desert." The western coast has considerable inland navigation, by means of the Senegal, the Gambia, and other large rivers emptying into the Atlantic. Niger also appears to be the channel of a considerable inland

commerce.

The

641. The Nile is the most remarkable among the rivers of Africa for its inland navigation; and Egypt is the only country where canals appear to have been formed for that purpose. It is now accessible only by two mouths-those of Rosetta and Damietta. The whole coast of its delta is lined with a succession of shallow lakes, which communicate with the sea, and are connected with the principal channel by canals. During high water, vessels of 40 tons navigate the stream without difficulty; but in the dry season, only boats can pass. The boat navigation extends to the cataracts, 600 miles from the mouth.

642. The celebrated Canal of Alexandria passes to this city, from the Rosetta branch of the Nile, along the neck of land between Lakes Mareotis and Aboukir. It furnishes the inhabitants with water during the flood of the Nile, which is preserved in cisterns for the rest of the year. The water is not sufficiently high for navigation more than 20 or 25 days in the year.

A canal was formerly cut from the Nile to the Red Sea, at Suez; but it has been entirely closed or disused of late years.

MARITIME WORLD.

643. The numerous islands which form the Maritime World, are extremely various in their character and magnitude. New Holland is by far the largest, and almost claims the name of con tinent, Those of Polynesia are generally very small.

[106] 644. Some of these islands have the lofty, rugged appearance of primary rocks; others are volcanic; and many of the low islands appear to be founded on coral. They are generally too small to require minute description in a system of geography, or too little explored to admit of it.

AUSTRALIA.

645. NEW-HOLLAND has scarcely been explored beyond the colony of New South Wales. The whole coast has a barren, repulsive appearance. In the colony, the land immediately bordering on the sea is flat and barren; but a few miles in the interior it is fine, and abounds in prairies almost destitute of timber. The Blue Mountains run along the coast, and separate the colony from the interior. They give rise to several large rivers, some of which flow into the interior, and are lost in extensive morasses; and it is singular that no large streams have been found emptying on the coast. From these circumstances it has been conjectured, that the whole island forms but a single basin, descending towards the centre into extensive morasses or lakes.

646. VAN DIEMEN'S LAND has a more favourable appearance on the coast than New-Holland, and is remarkable for the number of fine harbours. It is on the whole mountainous. It abounds in streams; and there are many large lakes among the mountains. The land is often good on the coasts; and in the interior, almost uniformly. Sometimes it spreads into extensive prairies, and every where presents great advantages for settlement and cultivation.

647. NEW-GUINEA, and the neighbouring islands north of NewHolland, are large, but have never been examined sufficiently to ascertain even the outline of their coasts.

NEW-ZEALAND comprises two islands. The surface is waving, gradually rising into mountains towards the centre. Mount Egmont, 12,000 feet high, is the loftiest peak. The northern island has a fertile soil; the southern is less productive.

NEW-CALEDONIA is an island of considerable size, surrounded by dangerous rocks and shoals. It presents a uniform, mountainous chain, with barren summits, interspersed with fertile valleys. The NEW-HEBRIDES are a group of small, rocky islands, which are yet fertile and populous.

POLYNESIA.

Islands North of the Equator.

648. The Pelew Islands, the Ladrones, and the Carolines, are groups of small islands, only remarkable for their fertility and fine climate.

The SANDWICH ISLANDS are a group of 9 or 10 islands. The whole are estimated to contain 6,000 square miles, of which Owhyhee contains 4,000. This island rises in the centre into the peaks of Mouna Kaah and Mouna Roah, which are estimated to be 16,000 feet above the level of the sea. The surface is generally waving, and the soil very fertile.

Islands South of the Equator.

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649. The FRIENDLY ISLANDS are a numerous group, consisting of more than 150 islands, the greater part of which are either rocks, or shoals, or barren desert spots. Some are fertile and delightful. The largest is Tongataboo, a low fertile island, which is said to be based on coral.

Otaheite is the principal of the SOCIETY ISLANDS. It has a fertile soil and delightful climate. In the interior it rises into inaccessible mountains, from which numerous streams descend.

(25.) Ice-fields of the Northern Ocean.

650. The level of the Ocean is the same in all parts of the world, except as it is varied by local causes. Inland seas which communicate with the ocean by a narrow strait, like the Baltic and Black Seas, are generally higher than the ocean,

in consequence of the streams flowing in from the land; and their beight is varied by the state of the streams at different seasons.

Those seas which open to the east, generally have a higher level than the ocean, in consequence of the winds and currents which continually come from the east, between the tropics. Thus the waters of the Gulf of Mexico, are from 20 to 23 feet higher than those of the Pacific near them; and the French engineers found the Red Sea 32 feet higher than the Mediterranean.

651. The depth of the ocean is extremely various, and its bed is evidently diversified with hills and valleys, mountains and plains. The tops of the mountains sometimes appear above the water, in the form of rocks, shoals, and islands; and vast spaces exist where the depth of the valleys cannot be sounded with the longest line. The greatest depth yet sounded is only 7,200 feet.

652. The waters of the ocean contain various salts, of which the most abundant [108] is common salt, or muriate of soda. The proportion is from 1-23d to 1-25th of the weight of the water, varying in different parts of the globe. It diminishes in going towards the cold and polar regions; and is sometimes greatly reduced by the fresh water of rains and streams, near the land.

653. The colour of the sea is generally a deep greenish blue; which varies much with the aspect of the sky, and is probably a reflection of its colour. In shallow water it becomes a light green, perhaps from the reflection of the bottom, or the fragments of sea-weed and marine plants it contains.

654. Numberless small animals are found to float on the surface of the sea, which are luminous at night, and produce a beautiful phosphorescence on the waves. The path of a vessel is a line of light, and the water which she throws up in her progress, or which rolls over her decks, appears like liquid fire. Sometimes myriads of luminous spots and stars, float and dance upon the water, and assume the most beautiful and fantastic appearance.

655. Around the poles the surface of the ocean presents only an expanse of ice. In latitude 700 there is usually a small quantity of ice floating at all seasons; and in latitude 800, we meet with those vast, permanent fields, which seem to claim the name of continents.

656. At the return of spring, the ice around the north pole fills up the bays of Hudson and Baffin, and extends in an irregular, waving line, from Newfoundland to Nova Zembla. It passes along the Labrador coast, usually preventing all access to the land as high as Hudson's Straits; and thence by Cape Farewell, north-east to Iceland and Jan Mayen, and east by Cherry Island, to Nova Zembla and Siberia. In Baffin's Straits, there is usually a deep bay formed by the ice. Between Iceland and Spitzbergen, a remarkable promontory of ice extends to the south, varying somewhat in its situation, which forms the boundary between the whale fisheries on the east, and the seal fisheries on the west. The same mass seems to extend along the whole northern coast of Asia, until it unites the two continents, north of Beering's Straits. During the summer the coast of Asia is accessible, and the ice may be penetrated as far as latitude 80°.

657. The icy continent of the southern hemisphere commences in a much lower latitude; and could never be penetrated beyond latitude 74° 15'.

658. From these continents vast fields of ice are frequently detached, which float off to sea. They are sometimes so extensive that their limits cannot be seen from the mast of a ship. From the shores of the polar regions, lofty masses, termed icebergs, frequently break off, and form floating islands. They obstruct the polar seas at all seasons, and are occasionally found as low as latitude 40°. Some of the icebergs are 600 feet in height; and hundreds have been seen at once, surrounding a vessel in all directions. The beauty of these objects, glittering in the sun-beams, surpasses every conception of one who has never seen them. 659. The ocean is continually moving in waves, tides, and currents. on the surface of the sea are perpetual, and are produced chiefly by the wind. They resemble the waving of a forest, and not the current of a stream; and their effect does not extend beyond 100 feet in depth.

The waves

660. Tides are those regular elevations and depressions of the ocean which occur twice in every twenty-four hours. They are produced by the attraction of the moon, combined with that of the sun.

The waters of the ocean are most elevated in that spot over whose meridian the moon has just passed. After the moon has risen at any place, the tide begins

to rise; soon after it has passed the meridian, the tide is highest, and [109] gradually sinks until it has set. The tide is high again when the moon is on the opposite side of the earth; and then falls again until it rises. The time, like that of the moon's rising, is about 50 minutes later every day.

661. At the new and full moon, the attraction of the sun is united to that of the moon, and causes higher tides than usual, which are called spring tides. About the first and last quarters, the attraction of the sun counteracts that of the moon, and causes the lowest, or neap tides.

662. The influence of the moon, like that of the sun, is felt_most_near the equator; the height of the tides diminishes in going from this circle, and near the poles, they are scarcely felt. In open situations, as in the islands of the Pacific Ocean, the tides rise at regular periods, and do not exceed one or two feet in height. When they meet a coast or bay, or pass through a narrow channel, the time is much varied, and the height often greatly increased.

In the British Channel, the tide sometimes rises 40 or 50 feet, and at the mouth of the Indus, sometimes 30. In the Bay of Fundy it rises to 60 feet, and often so rapidly that the cattle feeding on the shore have been drowned before they could escape.*

663. In inland seas and lakes, as in the Mediterranean and the Baltic, the quantity of water is so small, that all parts are equally attracted, and there is no perceptible tide. But in wide bays and harbours, and in seas open to the great western current, as in Baffin's and Hudson's Bays and the Red Sea, the influence of the tides is felt.

664. At the equator, the tides move from east to west following the apparent motion of the moon. In the Temperate Zones, they move towards the equator, as the centre of attraction.

665. The waters of the ocean are perpetually moving in currents, like winds, which seem to complete the circuit of the globe. Some appear to be permanent -others are variable, and change with the seasons, winds, or tides.

666. The most regular and extensive current on the globe, is that which flows constantly from east to west, generally extending 30 degrees on each side of the equator.

In the Pacific Ocean, its motion is uniform, and furnishes great aid to navigation. It passes south of New-Holland, and through the islands of Asia, to the coast of Africa and the Cape of Good Hope; but in consequence of the obstructions it meets, it produces numerous and variable currents in the Indian Ocean, which render the navigation dangerous.

667. In the Atlantic Ocean, the western current strikes the eastern projection of South America, and is divided into two portions; one of which flows along the coast of Brazil and passes into the Pacific, through the Straits of Magellan, with considerable rapidity. The other turns to the north, and passing through the Caribbean Sea, it enters the Gulf of Mexico, and flows out through the Bahama Channel in the celebrated Gulf Stream.

668. The Gulf Stream issues from the gulf, with the velocity of 4 or 5 miles an hour, and flows to the north-east, along the coast of the United States. As it proceeds northward, it recedes gradually from the shore, and diminishes in velocity. On striking the banks of Newfoundland, it turns to the south, and appears to mingle with the western current again, near the Azores. It probably reaches the north-eastern coast of Europe also; for the productions of tropical America are often thrown upon the coasts of Scotland and Norway; and in one in- [110] stance, the mast of a vessel burned in the West Indies, was cast upon the Hebrides. 669. There are two general currents which flow from the poles towards the equator. That which flows from the north pole, appears to strike the shores of Asia, and then pass round the North Cape into the Atlantic. It frequently throws whole forests of pines upon the coast of Iceland, which furnish the inhabitants with much of their fuel; and sometimes piles up huge masses of ice upon the shores, which are arrested in their progress to warmer latitudes.

* Morse.