BASIS ADRAS LDVBNTURE vn 



lies one of several resemblances between ihe valley 

 of the Euphrates and that of the Nile. But there 

 are important differences. The time of the annual 

 flood is reversed, the Nile being highest in autumn 

 and winter, and lowest in spring and early 

 summer. The periodical overflows of the Nile, 

 regulated by the great lake basins in the south, 

 are usually punctual in arrival, gradual ingrowth, 

 and beneficial in operation. No lakes are inter- 

 posed between the mountain torrents of the upper 

 basis of the Tigris and the Euphrates and their 

 lower courses. Hence, heavy rain, or an unusually 

 rapid thaw in the uplands, gives rise to the sudden 

 irruption of a vast volume of water which not 

 even the rapid Tigris, still less its more sluggish 

 companion, can carry off in time to prevent violent 

 and dangerous overflows. Without an elaborate 

 system of canalisation, providing an escape for 

 such sudden excesses of the supply of water, the 

 annual floods of the Euphrates, and especially of 

 the Tigris, must always be attended with risk, and 

 often prove harmful. 



There are other peculiarities of the Euphrates 

 valley which may occasionally tend to exacerbate 

 the evils attendant on the inundations. It is very 

 subject to seismic disturbances ; and the ordinary 

 consequences of a sharp earthquake shock might 

 be seriously complicated by its effect on a broad 

 sheet of water. Moreover the Indian Ocean lie- 

 wit liin the region of typhoons : and it. at the height 



