PART II.

DISTRIBUTION OF LAND.

Ir we take a glance at a map of the world, or examine an artificial globe, we are at once struck with the preponderance of water upon the earth's surface. Out of a total area of nearly two hundred million square miles, fifty-two millions, or about one-fourth only, is occupied by land. Of this land, again, three-fourths lie to the north of the equator. This is in itself a curious fact, but it is not all. Almost the whole of the land is really grouped on one side of the globe, so that not more than one twenty-seventh part has land opposed to it on the opposite side. If in an artificial globe we take Falmouth as a centre, we find that it is the pole of a hemisphere which contains forty-nine millions out of the fifty-two million square miles of land; Falmouth may, therefore, be taken as the centre of the terrestrial 1 hemisphere of the globe and a point in New Zealand is the centre of the aqueous 2 hemisphere.

Various theories have been propounded from time to time, in order to explain this preponderance of land in one hemisphere; and if this had been a constant fact in the history of the globe, some explanation might fairly have been looked for. But the present distribution of land and water is, if we may so term it, merely accidental. It is doubtless the most suitable in the present period of

the earth's history, but it has not always been the same. In the vast changes which produced the geological systems, the distribution of land has altered over and over again. It is probable, that at no previous period was it ever identically the same as now, and in succeeding ages it may possibly be again changed.

It is easy to conceive, that when land is raised above the sea, it will probably be of less density than when pressed down by a weight of superincumbent water. By the very act of upheaval it would be torn into fissures and rendered cavernous; and consequently, there is no need to have recourse to theories which suppose that the centre of gravity does not coincide with the centre of the earth's mass, or that the rocks which form the bed of the ocean are rendered more heavy by the presence numerous metallic veins.

of

If we now consider the forms of the great land-masses, we are struck with the fact, that they are all more or less triangular in shape; and if we descend to details, we see the same idea carried out in the peninsulas which fringe the borders of the northern continents. Another curious fact is, that most of the peninsulas, in whatever part of the world we meet with them, point to the south.

The great land-masses may be grouped into two sets of three each: the northern continents, embracing Asia, Europe, and North America; and the southern continents, embracing South America, Australia, and Africa. Looking merely at the outline of these continents, we find the northern continents differing from the southern masses in two or three important particulars. The northern continents are all much indented; each terminates in the south in three projections; and each has an archipelago of islands attached to

it. In Asia we have the three peninsulas of Further India, Hindostan, and Arabia, with the East India Archipelago. In Europe we have the peninsulas of Greece, Italy, and Spain, with the Grecian Archipelago. In North America we have the peninsula of California, the isthmus of Panama, and the peninsula of Florida with the West India Islands.

A deeply indented coast-line has a material effect upon the geography of a country or continent. The climate is brought under the influence of the surrounding body of water, and is thus rendered moist and equable. There are facilities for harbours and sea ports, and thus commercial activity is developed; while, on a large scale, deep indentations in a coast, by causing corresponding peninsulas and projections, tend to individualise the geography of a continent: to break up its monotony, to promote the establishment of separate nationalities, and thus to cause emulation in arts, to encourage exchange, and to advance civilisation. Viewing the subject in this light, it is important to notice the comparative length of coast in individual continents. In Asia there is one mile of coast to 528 square miles of surface; in Europe there is one mile to 187 square miles: in North America, the average is one mile of coast to 266 square miles of area. In the southern continents the length of coast is comparatively smaller. In South America, it is one mile to 440 square miles; in Africa one mile to 738 square miles of surface in Australia, one mile to 340 square miles of country.

The southern continents, therefore, as a whole, are remarkable for their compact outlines, and for the absence of numerous indentations. They differ from the northern continents also in the fact that they terminate towards the south in one point, instead of three ;

and that each has a large island near its southern extremity. Thus, Tierra del Fuego lies at the extremity of South America; Madagascar, near the southern point of Africa; and Van Diemen's Land, at the southern extremity of Australia. It has also been remarked that each of the southern continents is distinguished by having a large bulge or deep bend in its western side: it is sufficient to mention the Gulf of Guinea, the Australian Bight, and the large bend on the west side of South America. "Text-Book of Physical Geography," by WM. LAWSON.

1. TERRESTRIAL, earthly. Terrestrial hemisphere, a half sphere composed almost entirely of land. (Lat. terra, the earth.)

2. AQUEOUS, watery. Aqueous hemisphere, a half sphere composed almost entirely of water. (Lat. aqua, water.)

3. SUPERINCUMBENT, lying above. (Lat. super, above, and cumbo, to lie down.)

The word

4. ARCHIPELAGO, a sea abounding with small islands. literally means chief sea, and was the name given by the Greeks to the sea lying between their own country and Asia Minor; this sea was studded with islands; hence our present use of the word archipelago, which is now frequently applied to islands themselves when clustered thickly together.

SPRINGS, RIVERS, LAKES.

Of the total quantity of water which falls upon the earth in the form of snow or rain, a portion is carried off by rivers into the sea, another portion is evaporated and carried back into the atmosphere; the remainder sinks into the ground. This portion is not lost, it circulates through the crust of the earth, in some parts forming pools, in others, underground rivers. These rivers differ from streams on the earth's surface, for they sometimes sink to great depths, and then rise again through hydraulic1 pressure. When water reappears again at the