More than 860,000,000 of human beings are scattered over the face of the earth, of all nations and kindreds and tongues; and in all stages of civilization, from a high state of moral and intellectual culture, to savages but little above the animals that contend with them for the dominion of the deserts and forests through which they roam. This vast multitude is divided into nations and tribes, differing in external appearance, character, language, and religion. The manner in which they are distributed, the affinities of structure and language by which they are connected, and the effect that climate, food, and customs may have had in modifying their external forms, or their moral and mental powers, are subjects of much more difficulty than the geographical dispersion of the lower classes, inasmuch as the immortal spirit is the chief agent in all that concerns the human race. The progress of the universal mind in past ages, its present state, and the future prospects of humanity, rouse the deep sympathies of our nature for the high but mysterious destiny of the myriads of beings yet to come, who, like ourselves, will be subject for a few brief years to the joys and sorrows of this transient state, and fellow-heirs of eternal life hereafter.

Notwithstanding the extreme diversity, personal and mental, in mankind, anatomists have found that there are no specific differences—that the hideous Esquimaux, the refined and intellectual Circassian, the thick-lipped swarthy Negro, and the fair blue-eyed Scandinavian, are mere varieties of the same species.

In the present state of the globe a third part of its surface only is occupied by land, and probably not more than a fourth part of that is inhabited by man, but animals and vegetables have a wider range. The greater part of the land is clothed with vegetation and inhabited by quadrupeds, the air is peopled with birds and insects, and the sea teems with living creatures and plants. These organized beings are not scattered promiscuously, but all classes of them have been originally placed in regions suited to their respective wants. Many single animals and plants are indigenous only in determinate spots, while a thousand others might have supported them as well, and to many of which they have been transported by man.

The atmosphere supplies the vegetable creation with the principal part of its food; plants extract inorganic substances from the ground, which are indispensable to bring them to maturity.

The black or brown mould, which is so abundant, is the produce of decayed vegetables. When the autumnal leaves, the spoil of the summer, fall to the ground, and their vitality is gone, they enter into combination with the oxygen of the atmosphere, and convert it into an equal volume of carbonic acid gas, which consequently exists abundantly in every good soil, and is the most important part of the food of vegetables.

Taking the natural divisions of the continent alone into consideration, Central America may be regarded as lying between the 7th and 20th parallels of north latitude, and consequently in a tropical climate. The narrow tortuous strip of land which unites the continents of North and South America stretches from S.E. to N.W. about 1000 miles, varying in breadth from 30 miles to 300 or 400.

As a regular chain, the Andes terminate suddenly at the plain of Panama, but as a mass of high land they continue through Central America and Mexico, in an irregular mixture of table-lands and mountains. These table-lands, however, differ from those in the Andes of South America, inasmuch as they are not bounded on each side by Cordilleras following the direction of the chain, but are traversed by ranges running over them in all directions, or studded by mountains. The mass of high land which forms the central ridge of the country, and the watershed between the two oceans, is very steep on its western side, and runs near the coast of the Pacific, where Central America is narrow; but to the north, where it becomes wider, the high land recedes to a greater distance from the shore than the Andes do in anyother part between Cape Horn and Mexico.

Some thinner portion of the crust of the globe under the meridians that traverse the continent of America from Cape Horn to the Arctic Ocean must have yielded to the expansive forces of the subterranean fires, or been rent by the contraction of the strata in cooling. Through this the Andes had arisen, producing the greatest influence on the form of the continent, and the peculiar simplicity that prevails in its principal mountain systems, which, with very few exceptions, have a general tendency from north to south. The continent is 9000 miles long, and, its form' being two great peninsulas joined by a long narrow isthmus, it is divided by nature into the three parts of South, Central, and North America; yet these three are connected by the mighty chain of the Andes, but little inferior in height to the Himalaya, running along the coast of the Pacific from within the Arctic nearly to the Antarctic circle. In this course every variety of climate is to be met with, from the rigour of polar congelation to the scorching heat of the torrid zone; while the mountains are so high that the same extremes of heat and cold may be experienced in the journey of a few hours from the burning plains of Peru to the snowclad peaks above. In this long chain there are three distinct varieties of character, nearly, though not entirely, corresponding to the three natural divisions of the continent.

There is great similarity in the birds of the northern parts of the old and new continents, and many are identical. Towards the south, the forms differ more and more, till in the tropical and south temperate zones of Asia, Africa, and America they become entirely different, whole families and genera often being stationary within very narrow limits. Some birds, however, are almost universal, especially birds of prey, waders, and sea-fowl.

The bald buzzard is in every country, from Europe to Australia; the Chinese gosshawk inhabits the American continent, and every station between China and the west coast of Europe; the peregrine falcon lives in Europe, America, and Australia; the common and purple herons are indigenous in the old continent and the new; and the flamingo fishes in almost every tropical river. Many of the sea-fowl also are widely spread : the wagel-gull is at home in the northern and southern oceans, and on the coasts of Australia. Captain Beechey's ship was accompanied by pintadoes during a voyage of 5000 miles in the Pacific; and even the common house-sparrow is as much at home in the villages in Bengal as it is in Britain. Many more instances might be given, but'they do not interfere with the general law of special distribution.

Birds migrate to very great distances in search of food, passing the winter in one country and the summer in another, many breeding in both.

The great central plain of North America, lying between the Rocky and Alleghanny Mountains, and reaching from the Gulf of Mexico to the Arctic Ocean, includes the valleys of the Mississippi, St. Lawrence, Nelson, Churchill, and most of those of the Missouri, Mackenzie's, and Coppermine rivers. It has an area of 3,240,000 square miles, which is 240,000 square miles more than the central plain of South America, and about half the size of the great plain of the Old Continent, which is less fertile; for, although the whole of America is not more than half the size of the Old Continent, it contains at least as much productive soil.

This plain, 5000 miles long, becomes wider towards the north, and has no elevations, except a low table-land which crosses it at the line of the Canadian lakes and the sources of the Mississippi, and is nowhere above 1500 feet high, and rarely more than 700. The character of the plain is that of perfect uniformity, rising by a gentle regular ascent from the Gulf of Mexico to the sources of the Mississippi, which river is the great feature of the North American low lands. The ground rises in the same equable manner from the right bank of the Mississippi to the foot of the Rocky Mountains, but its ascent from the left bank to the Alleghannies is broken into hill and dale, containing the most fertile territory in the United States.

The labyrinth of islands that is scattered over the Pacific Ocean for more than 30 degrees on each side of the equator, and from the 130th eastern meridian to Sumatra, which all but unites this enormous archipelago to the continent of Asia, has the group of New Zealand or Tasmania, and the continent of Australia, with its appendage, Yan Diemen's Land, on the south ; and altogether forms a region which, from the unstable nature of the surface of the earth, is partly the wreck of a continent that has been engulfed by the ocean, and partly the highest summits of a new one rising above the waves. This extensive portion of the globe is, in many parts, terra incognita; the Indian Archipelago has never been explored, and, with the exception of our colonies in New Holland and New Zealand, is little known.

The continent of New Holland, 2400 miles from east to west, and 1700 from north to south, is divided into two unequal parts by the tropic of Capricorn, and consequently has both a temperate and a tropical climate. New Guinea, separated from New Holland by Torres Straits, and traversed by the same chain of mountains with New Holland and Van Diemen's Land, is so perfectly similar in structure, that it forms but a detached member of the adjacent continent.

According to the natural division of the continent, North America begins about the 20th degree of north latitude, and terminates in the Arctic Ocean. It is longer than South America, but the irregularity of its outline renders it impossible to estimate its area. Its greatest length is about 3100 miles, and its breadth, at the widest part, is 3500 miles

The general structure of North America is still more simple than that of the southern part of the continent. The table-land of Mexico and the Rocky Mountains, which are the continuation of the high land of the Andes, run along the western side, but at a greater distance from the Pacific; and the immense plains to the east are divided longitudinally by the Alleghanny Mountains, which stretch from the Carolinas to the Gulf of St. Lawrence, parallel to the Atlantic, and at no great distance from it. Although the general direction of the two chains is from south to north, yet, as they maintain a degree of parallelism to the two coasts, they diverge towards the north, one inclining towards the north-west, and the other towards the north-east. The long narrow plain between the Atlantic and the Alleghannies is divided, throughout its length, by a line of cliffs not more than 200 or 300 feet above the Atlantic plain—the outcropping edge of the Second Terrace, or Atlantic Slope, whose rolling surface goes west to the foot of the mountains.

The only river system of importance in western Asia is that of the Euphrates and Tigris. In the basin of these celebrated streams, containing an area of 230,000 square miles, mounds of rubbish on a desolate plain are the only vestiges that remain of the great cities of Nineveh and Babylon. Innumerable ruins and inscriptions, also records of the glory of times less remote, have been discovered by adventurous travellers, and bear testimony to the truth of some of the most interesting pages of history. The Euphrates, and its affluent the Merad- Chai, supposed to be the stream forded as the Euphrates by the 10,000 Greeks in their retreat, rise in the heart of Armenia, and, after running 1800 miles on the table-land to 38° 41′ of north latitude, they join the northern branch of the Euphrates, which rises in the Gheul Mountains, near Erzeroum. The whole river then descends in rapids through the Taurus chain, north of Rumkala, to the plains of Mesopotamia.

The Tigris comes from Dearbeker, more to the east, and, after receiving auxiliaries from the high lands of Kourdistan, it pierces the Taurus Mountains at Mosul, and descends rapidly in a tortuous course to the same plains, where it is joined by many streams from the Lusistán Mountains, some of which are navigable, and may ultimately be of great commercial importance. The country through which they flow is extremely beautiful, and rich in corn, date-groves, and forest-trees.