274 RELATIONS OF AIR AND WATER TO TEMPERATURE AND LIFE. 



Farther to the iioitbeast rise the great rivers of China, theHoaug ho* 

 and Yang-tse-kiang. Their valleys are separated by high chains of 

 mountains, extending in a northwest and southeast direction. The 

 Hoang-ho runs north and east through the temperate zone of China, 

 and the Yang-tse-kiang south and east through the semitropical 

 regions of middle China. As they gradually approach, they inclose a 

 great valley and become the arteries of the superabundant life of the 

 Empire. The eastern 3)art of this great valley, watered by the winds 

 from the China Sea, is crossed from northeast to southwest by parallel 

 ridges, from which numerous streams descend. The valley of eastern 

 China is thus abundantly watered and the rich soil yields bountifu[ 

 croi)s. For thousands of years this region has been the home of the 

 Chinese, a self-dependent w^orld. It is a limited territory of 1,300 000 

 square miles area, no larger than the valley of the Mississippi; yet it 

 sustains a population of 400,000 000 or one-third of the people of the 

 globe. 



North of the Kuen Luen Mountains, and the valley of the Hoang-ho 

 and south of the Thian Shan, is the plateau of the Tarim, sometimes 

 called Eastern Turkestan. It is much lower than Tibet, and is trav- 

 ersed by cross-ranges of hills or low mountains, through which flows 

 the river Tarim. Little rain falls on this plateau, the sand from the 

 desert is gradually covering the fertile valleys, the ancient lakes are 

 now little more than salt marshes, and where formerly lived bands of 

 Huns and Vandals that over-ran Europe, now only a few shepherds find 

 a scanty living. This part of the world seems exhausted. '• Without 

 a shrub or tree or blade of grass," and no longer fit for the residence 

 of man, it has become the sole home of the wild horse and the yak. 

 East of this plateau of Tarim are the deserts of Gobi and Mongolia, 

 which extend far eastward toward the sea of Japan, a high range of 

 mountains separating Mongolia, however, from the seacoast, so that 

 only dry winds blow over these great deserts. 



North of the Thian Shan and the Altai mountains is the great i^lniii 

 of Siberia. It starts from a lower level than that of the Tarim desert 

 and descends Avith a gradual slope northward for 1,500 miles to the 

 Arctic Ocean. These plains resemble in some respects the great plains 

 of the United States, but the latter slope toward the east and south 

 with a climate growing continually wnriner, while the Siberian plains 

 slope toward the north, the temperature growing (continually colder. 

 The winds in summer blow from the Arctic Ocean over these plains to 

 the Altai Mountains, while in the winter they blow from the mountains 

 to the ocean. There is a slight evaporation from the Arctic Ocean, but 

 the temperature of Siberia is so low and the summers so short that 

 the i)lains require comparatively slight rain-fall to fertilize them. 



There is a large portion of Asia, Arabia, Persia, Turkestan, includ- 

 ing Caspian and Aral seas, to which we have not particularly referred 

 because it is entirely outside of the influence of either the monsoon, 



