Africa is somewhat triangular, with its base towards Asia and its apex pointing southward. It is bounded northwards by the Mediterranean Sea, and at its east side by the Red Sea and Indian Ocean, while the Atlantic flows on its south-west side. In Africa is the largest desert in the world, the Great Desert of Sahara; it occupies nearly all the northern part, the southern has but few mountains of great extent, but from their elevation and the amount of waters brought down by rivers, it is supposed that the centre has very high table lands. At the north-western part is an extensive mountain system (the Atlas) covering with its branches nearly 500,000 square miles, and sending its slopes to bound the great Desert northwards.
The great tract of land comprising North and South America extends in a longitudinal direction pretty nearly north and south through 130 degrees of latitude, or nearly 8000 miles. This great tract is divided by a narrow neck of land (the Isthmus of Panama) into two pretty equal portions; the northern part is peculiar, from containing a number of lakes of immense extent, deserving well the name of inland seas, and both northern and southern divisions for the great number and extent of their water-courses. The whole of this great tract of land is traversed from end to end by an extensive chain of mountains, the longest in the world; at its southern part it forms the Andes, from which a range is continued through the Isthmus, and onwards to form the Rocky Mountains. In the southern division this immense chain passes on the west side of the land close to the sea, is of great elevation in some parts, has some of the highest mountain peaks in the world, and volcanoes also, the highest being in the Andes (Popocatapetl is about 16,000 feet high); but from the western side of the continent the land descends gradually to the eastern. In South America are some of the highest table-lands known, great elevated tracts in connection with the mountain ranges.
Australia in its interior is but little known, but the whole aspect of the island appears to be flat, and to have but little elevation, while Greenland and the great tracts of the northern regions beyond, deserve more the name of glaciers, being almost entirely a mass of barren rocks and snow.
The water-courses of these various great tracts of land are all determined by the formation of the surface, but the amount of water which is carried into the oceans by the rivers of any district is always in proportion to the amount of vegetation in that district; thus in Europe, Asia, and America, the number and extent of these correspond with the great fertility of the soil, while the northern and western part of Africa—the Great Desert—give off scarcely any of adequate extent, the Nile appearing to receive its supply from the central parts further south. The reason of it is this: wherever there is vegetation, either in the form of grassy prairies or forests, there is also a great reduction of temperature from the radiation and evaporation, and the consequent formation of rain, dew, or snow, which falling on the ground produces streams, &c.
Excepting the great tracts of land named, and islands too numerous to be mentioned, the whole surface of the earth is covered with water, the great divisions of which (called Oceans) are, the Arctic Ocean, to the north of Europe, the Atlantic, between America, Europe, and Africa, the Pacific between Asia and America, and the Indian Ocean between Africa and Australia.
The foregoing is a very bare outline of the land and water covering the surface; it may suffice, however, to call to mind the main features of the earth as it is now disposed. There can be little doubt that the great variety of climate, whether hot or cold, moist or dry, is one of the greatest sources of happiness that can be well imagined; it stimulates to research, travel, and inquiry into the works of God; every change experienced tends to make man search for further change, every new scene makes him compare it with others; and the acquirement of a knowledge of places, and a general idea of the whole world, expands his mind, enables him to appreciate the good gifts he has received, and affords a source of satisfaction beyond almost any other kind of enjoyment.
[THE WATERS.]
