We shall now consider each of these inequalities in detail.
6. In regard to the bottom of the sea, we may at pre sent remark, that it is diversified by many inequalities; which, however, are not so special as those on the sur face of the dry land.
The ocean covers about three-fifths of the whole earth, so that there is but a comparatively small portion of it elevated above the surface of the water. Even this does not form a connected whole ; on the contrary, it is divided into a number of detached masses, to which geographers have given different names: the larger are denominated continents, the smaller, islands.
The geographic division of the earth into continents is not quite correct. Thus Europe and Asia, which form but one continent, are by geographers divided into two ; whereas America, which forms two very dis tinct continents, having their natural boundary at the Isthmus of Darien, is considered as one. Europe and Asia should therefore be considered as forming one con tinent, and America two. Africa, on the contrary, is well characterised as a distinct continent.
The great inequality of the distribution' of tile land, which rises above the surface of the ocean, deserves at tention. 11 we conceive the earth divided into two equal parts by the equator, we shall find a melt strik ing difference in the proportion of land on its north. and south sides: the southern half is almost entirely composed of watch ; but in the northern, the greater 3 G portion is land. The proportion of land on the north and south sides of the equator, is as 3 to 4.. It has been also observed, that if the earth be divided by a meridian line, the proportion of land and water on op posite sides is strikingly different ; there being always a preponderance of water in the one side, and land on the other.
This great accumulation of land in the northern half of the globe, suggested to some speculators the idea of the existence of a southern continent ; as they conceiv ed it to he impossible that the equipoise of the earth could otherwise remain undisturbed. The illustrious Cook, however, has shown, that even beyond 71° S. latitude, there is no appearance of a continent ; and that these dreary regions of water and ice are only di versified by a few islands.*
7. The most general inequalities observable on the surface of the dry land are, as we have already ob served, high land and low land. By the first, we un derstand a lofty, uneven, and widely extended mass of land : by the second, a great and widely extended low and flat country.
In Europe, we find but two high lands and one low land. The one is the great European or Southern ; the other the Scandinavian or Northern. The one has its middle point in Switzerland, in the Tyrol, and_the .A?ps of Savoy. Hence it passes through three-fourths of France ; traverses the whole of Portugal and Spain ; includes nearly two-thirds of ; the greater part of Italy ; and also part of Hungary and Turkey ; and terminates on the borders of the Black Sea. The course of this high land determines that of the great low land. Saxony lies nearly on the border of this low land or plain. It passes through the north part of Saxony, to the East or Baltic Sca. It also passes by the foot of the Hartz Mountains; through the upper part of Westphalia ; and further, through the 'whole of Holland, the Netherlands, and a small part of France ; it even reaches the cast coast of this island. It extends very considerably towards the north, including in its course, Prussia, Poland, and nearly all Russia in Europe ; and reaches to the Uralian Mountains, includ ing tl,e greater part of Moldavia.
The other high land rises in Norway and Sweden ; comprehends a portion of Russia ; and extends, with sonic. interruption, to the Uraiian mountains.
High and low lands might also be pointed out in the othei continents.
8. Ei cry high land is composed of what may be term ed alpine, mountainous, and hilly land ; and sometimes of small plains. TM low land, on the contrary, consists principally of plains ; hut we find in it, also, sometimes mountainous and hilly land, and, very rarely, small moun tain groups. Here the constituent parts are directly re versed ; in high land, the alpine country forms the pre dominating feature, hut in low land the plain is the cha racteristic appearance.