8o8 THE POPULAR SCIENCE MONTHLY. 



WHAT IS KNOWN OF THE EARTH.* 



By Lieut. -General R. STEACHEY, F. R. S. 



SO 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 por- 

 tion of Central Africa where Stanley is for the present moment 

 lost to view, no considerable part of the earth's surface is unex- 

 plored, 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 civil- 

 ized 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 Si- 

 beria 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 conti- 

 nent, 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 83^° 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 cool- 

 ing 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 con- 

 ditions of surface, from which have arisen, as direct consequences, 



* From " Lectures on Geography," delivered before the University of Cambridge. 



