Page:Popular Science Monthly Volume 33.djvu/828



O thorough has been the success with which recent labors of geographical research have been prosecuted, that it would now be hardly possible to describe what is known of the earth, otherwise than by pointing to what is still unknown, and this might be summarized in a very few words.

Besides the interior of Borneo and New Guinea, and the portion of Central Africa where Stanley is for the present moment lost to view, no considerable part of the earth's surface is unexplored, with the exception of the polar regions, which have till now proved inaccessible. The maps of the interior of Africa now supply trustworthy representations of a vast system of rivers, lakes, and mountains, till recently wholly unknown to the civilized world, and what remains to be done is little more than to fill in the details of well-ascertained large outlines. Australia has been crossed and recrossed in many directions. The darkness which so long enveloped Central Asia has been entirely cleared away, and, though parts of Thibet are yet to be visited, the true nature of the central plain lying between that country and Siberia is completely known. The geographical features of North America are little less perfectly mapped than those of Europe; but large parts of the interior of South America, much of which is covered by forest, are still unsurveyed. The southern border of the North Polar Sea, and the very complicated system of islands and channels along the northern margin of the American continent, between Bering Strait and Greenland, have been precisely delineated, and the boundary of the same sea along northern Asia has also been determined. The highest northern latitude reached is about 83½° north—that is, within five hundred miles of the pole. The nearest approach to the south pole has been in 78° 11' south, but the difficulties arising from climate have till now stood in the way of any satisfactory survey of the land seen at some few points in the antarctic area.

The figure of the earth, and its existing features, have had their origin in a former state of the planet, during which it has been subject to the gradual changes that accompanied its cooling from a previously much higher temperature. The forces of nature which are still at work, including the most wonderful of all, life, have operated upon the globe while it thus passed through the stages which have led to what it now is; producing varied conditions of surface, from which have arisen, as direct consequences,