IRfvers an& fflooDs, 157 



river of South America, the Amazon, is an in- 

 stance of a river of this class. A certain 

 number of the smaller rivers that feed it lie 

 in the area of rainfall during the whole of the 

 year; for instance, the streams of the upper 

 Amazon are being 1 fed by rains at one season 

 of the year, when those feeding the river lower 

 down are at the lowest stage. When the rainy 

 season prevails in the upper section of the 

 river the dry season prevails farther down, 

 while at another season of the year these con- 

 ditions are reversed. Therefore, though the 

 Amazon has a larger drainage basin than any 

 other river in the world, and in some parts the 

 yearly rainfall is 280 inches, there is no very 

 great fluctuation in the stages of water. The 

 Orinoco River, which flows through Vene- 

 zuela, and whose drainage area is largely cov- 

 ered with mountains, has a greater fluctuation 

 than any other river, the difference between 

 high and low water amounting to seventy feet. 

 The River Nile has an annual rise of from 

 fourteen to twenty-six feet. This river is the 

 sole dependence of the inhabitants of lower 

 Egypt, and their sustenance depends upon the 

 height to which the river rises; if it does not 

 rise high enough the agricultural lands are 

 not sufficiently irrigated, and if it rises too 

 high their crops are destroyed by the floods. 

 In this section they depend entirely upon the 

 overflow of the Nile for irrigation, and not 



